Weakness in the oil and gas sector forced to write down £440m with the Anglo-American engineering group still loss-making despite a rise in revenue.

Revenues in the first half increased 7 per cent to £2.8bn compared with the same period last year due to strong growth in its clean energy and environment and infrastructure businesses.

However, revenues in its US and gas business fell 55 per cent with delays and cancellations of key contracts also leading to lower margins.

The company reported a pre-tax loss of £446m for the half compared with a profit of £73m a year earlier.

It maintained its guidance for the full year but predicted like-for-like revenues will be down “double-digit” compared with last year.

Shares rose 3 per cent to £480.70 on Tuesday morning as the results beat analyst expectations both for revenues and profits. Analysts at Liberum noted that revenues from solar and the UK North Sea were at record levels but were offset by weak performance from Americas oil and gas.

“Our industry continues to face very challenging conditions, with capital projects across natural resources markets being delayed and cancelled in many parts of the world,” said , chief executive.

reflect the toxic overspill of the oil sector’s pain. Companies that provide services and equipment for the offshore and shale industries, such as Wood Group or Weir, have been hammered as energy majors slash investment spending in response to the oil price fall.

Amec designs, builds and maintains engineering equipment, and relies on the oil and gas industry for much of its business.

The Anglo-American group parted ways with chief executive Samir Brikho in January, just over a year after he created it through a $3bn merger. It has pledged to cut costs and deleverage its balance sheet, with sales of non-core assets planned to help cut debt.

Amec recognised £440m of impairments during the first half. The company aims to complete £500m of disposals by next June to help halve its net debt.

However, it admitted that, excluding any benefit from disposals, net debt will be higher than previously forecast at the end of this year at about £1.1bn.

Mr Lewis said: “We continue to benefit from the diversity of our platform and we remain on track to deliver the operational guidance we gave at the beginning of the year.

“I have initiated a wide-ranging review of the strategy, our organisation structure and cost base — which we are now part-way through. I expect to update investors on these issues in the autumn.”