Tata Steel is planning to sell its Long Products division, which employs thousands of workers at several sites in the UK.

The steel giant said it had signed a Memorandum of Understanding with the Klesch Group, an industrial company which operates across Europe.

The planned sale covers several UK-based sites including Tata Steel's Scunthorpe steelworks, mills in Teesside, Dalzell and Clydebridge in Scotland, an engineering workshop in Workington and a rail consultancy in York, as well as other operations in France and Germany.

About 6,500 people are employed at Long Products Europe and its distribution facilities, supplying products for industries including construction and excavation.

Unions said they were disappointed with the way the announcement had been handled and were seeking talks to discuss any impact on jobs.

Karl Koehler, chief executive of Tata Steel's European operations, said: "We will now move into detailed due diligence and negotiations, though no assurance can be given about the outcome. We will regularly engage with our employees and other stakeholders throughout this process, and we will consult with the trade union representatives and works councils.

"We are making huge strides on our strategic journey to become a premium, customer-centred steel company thanks to investment in equipment, technology and customers, together with the substantial contributions from our employees.

"We've improved the competitiveness of Tata Steel's European operations, including Long Products Europe which now supplies more of the innovative steel rail, rod, plate, sections and special profile products demanded by customers.

"Accelerating the pace of innovation on advanced steel solutions, helping our customers succeed in their markets and creating a sustainable asset base requires significant capital and expertise.

"We have therefore decided to concentrate our resources mainly on our strip products activities, where we have greater cross-European production and technological synergies.

"We want to build a sustainable business in the UK and further develop our mainland Europe business and we are committed to providing the necessary leadership and financial resources to achieve that."

Roy Rickhuss, general secretary of the steelworkers' union Community, said: "We're extremely disappointed with the way that Tata Steel have handled this announcement, which does not reflect well on Tata's values.

"However, I am pleased that Tata Steel chairman Cyrus Mistry has now agreed to meet the unions and I hope this can take place soon so that we can start to address the understandable worries and concerns of our members, their families and communities."

Community, Unite and the GMB said in a joint statement: "Tata Steel has failed to consult at all with the trade unions before making this move, which could have serious consequences for employees and contractors right across Tata Steel, not just within the Long Products business that it wants to sell.

"The unions have been treated with contempt in this process as the level of consultation that we would expect ahead of such a major strategic announcement has not taken place.

"We were made aware of this fait accompli two days ago, which is neither within the spirit nor the letter of long-standing Information and Consultation or European Works Council agreements.

"We want Tata Steel to take a step back and carry out the consultation with its unions, which it should have been doing in recent months when it was preparing to sell its assets.

"The fact that Tata Steel wants to abandon half of its European operations and pull out of an entire strategic market does not bode well for the future and ends Tata Steel's vision to be a global steel player.

"Tata Steel has long emphasised that its European operations are 'one company' but today's announcement is the final nail in that concept's coffin.

"We are calling on the Government to intervene in the public interest to ensure a future for industrial assets of strategic importance to the UK's construction, infrastructure and manufacturing base.

"Our immediate thoughts are with those employees, contractors, families and communities that are worried about their future and we would urge Tata Steel to follow its own Code of Conduct and act in the interests of the communities in which it operates by engaging in meaningful consultation with its trade unions before it progresses the terms of this Memorandum of Understanding."

The Klesch Group is a global industrial commodities business, with three divisions specialising in the production and trading of chemicals, metals and oil.

Founded in 1990 and headquartered in Geneva, it employs more than 2,000 people across 30 locations in more than 17 countries around the world.

Business Secretary Vince Cable said: "The next few months will be a time of uncertainty for the company and employees. The proposed sale shows the harsh reality of trading conditions in parts of the steel industry.

"I met the global head of Tata in India this week and he has personally re-affirmed to me his company's commitment to the British steel industry and to investing substantially in Port Talbot and strip steel.

"My officials and I will continue to work closely with Tata Steel and seek to meet the potential buyer, Klesch, to understand more about their plans. We welcome Klesch's stated intention to support the continuity of the business."

Tom Greatrex, Labour MP for Rutherglen and Hamilton West, home to Tata's Clyde Bridge Steelworks, said: "The announcement that Tata Steel are in the process of selling their long products steel division - including Clyde Bridge in Cambuslang - is a bolt from the blue, with no consultation with unions and workers, despite the European Works Council standards Tata have signed up to.

"It is a huge concern for those employed at Clyde Bridge, their families and contractors who rely on the steelworks for their living. With a secret and sudden deal, steelworkers are understandably concerned about their jobs being at risk.

"The failure to consult beforehand has heightened fears that this move will put an historic and strategically important industry in Scotland at risk."

Iain Wright, shadow minister for industry, said: "This announcement will create uncertainty and will be deeply worrying for the thousands of people affected. It is crucial that Tata Steel works with employees, trade unions and others and that jobs are safeguarded and that ministers take a lead.

"The UK steel industry supports thousands of skilled jobs. It is an essential part and foundation of a modern economy with manufacturing at its heart. That's why Labour has urged the need for a proper industrial strategy supporting our key sectors.

"Long products represent an important part of the UK steel industry - we want to see this maintained and further developed in this country and will work constructively to ensure this happens."

Frank Roy, Labour MP for Motherwell and Wisham, called on the UK and Scottish Governments to intervene, adding: "Today's announcement is a major blow to those working at Dalzell and Clydebridge steelworks and the other affected sites through the UK.

"I have profound concerns about what this course of action will mean for the future of the UK steel industry, the company, both Long and Strip Products divisions, and for the lives of the workforce, their families and our communities."