Shares in British product-testing firm Intertek Group jumped by nine per cent to their highest level since May after it posted an improvement in first-half underlying revenue growth and maintained its full-year guidance.

Intertek, which tests anything from oil to children's toys to check they comply with regulatory standards, said its underlying revenue grew 1.4 per cent to £1.06 billion, from £1.02bn, in the first-half of its financial year.

Chief executive Andre Lacroix noted a strong performance in its products-related business, particularly in consumer goods, electricals and commodities, which had helped offset challenging conditions in its oil and gas capital spending business.

Energy companies have been slashing investment budgets following a plunge in oil prices.

"This is obviously a situation that we cannot ignore. This is 10 per cent part of our earnings in total," Mr Lacroix said.

"It is reasonable to believe that the capex reductions will continue in the next few months ...We have to cycle through that time, and over time minerals and oil and gas will start growing again," he added.

Pre-tax profit rose to £139.1 million in the first half of its financial year, compared with £119.8m a year earlier.

"There has been momentum on the organic growth as we have moved through the quarter and there has been a very strong margin performance," said Numis analyst Steven Woolf.

"The results themselves are towards the top end of expectations so there's an element of recovery on that side of things," he added.