Qatar is failing to deliver on reforms for its migrant workers a year after the wealthy Gulf nation announced plans to improve conditions for low-paid labourers building its highways, hotels, stadiums and skyscrapers, Amnesty International has said.

In a new briefing paper, the London-based rights group criticised the 2022 World Cup host for making no substantive changes on some labour issues, including the controversial "kafala" employee sponsorship system, and delivering only partial progress in other areas.

The report was released a day after three major World Cup sponsors - Adidas, Coca-Cola and Visa - publicly pressured football's world governing body Fifa to push Qatar to do more to improve labour conditions.

Qatar is being transformed by a building boom fuelled by its vast oil and natural gas wealth.

Like other energy-rich Gulf nations with relatively small local populations, it relies on well over a million guest workers, many of them drawn from South Asian nations including India and Nepal.

Qatar responded to Amnesty's latest report by saying it disagrees with some of the claims and asserting it has made "significant changes" to improve working conditions.

The government believes that promoting human rights for guest workers and others is a "strategic choice and the backbone of the comprehensive constitutional, economic, social and cultural reform policy" of the country, the Ministry of Labour and Social Affairs said.

It cited a number of changes made over the past year, including efforts to boost the number of labour inspectors, provide better housing for workers and crack down on employers and labour recruiters who break Qatari law.

"We are all dealing with the unique challenges brought about by rapid economic growth and the high population of expatriate workers seeking better opportunities," the ministry said, adding that it is "committed to effective and sustainable change".

In May 2014, officials outlined plans for legislation that could end in its current form the kafala system that ties expatriate workers to a single employer.

The draft law also would allow workers to obtain exit visas without having to secure their employers' consent. Rights groups say the existing policies leave workers open to exploitation and abuse.

Amnesty says the reforms are not coming fast enough.

"We've had a year, and not much has changed. For us that's a really important thing," Amnesty's Gulf migrant rights researcher Mustafa Qadri said. "The situation has probably gotten worse because you have more workers now. ... There's a matter of urgency."

The Opec member state has come under intense scrutiny over its labour policies since winning the right to host the World Cup in 2010. Sepp Blatter, who is hoping to win a fifth term as Fifa president in elections next week, pressed Qatar's emir in March to do more to improve working conditions.

Fifa welcomed the Amnesty report, and said it along with trade unions and rights groups will continue to push Qatar to enact reforms and abolish the kafala system.

"Fifa has repeatedly urged publicly and with the highest authorities in Qatar that fair working conditions for all workers in Qatar are imperative," it said.

Statements by Adidas, Coca-Cola and Visa yesterday will pile further pressure on Fifa and Qatar to improve working conditions.