Lockheed Martin has boosted its profit forecast as production of its controversial F-35 stealth fighter increases.

The world’s biggest defence company upgraded its expectations as it posted half-year figures, which showed revenue up 8pc to $23.7bn (£18.2bn), though profit from continuing operations was flat at $1.7bn.

The American arms giant said sales in its aeronautics division, which heads the F-35 programme, rose by almost $1.2bn to $9.3bn, an increase it attributed mainly to ramping up production of the new stealth jet.

As a consequence of growing demand, Lockheed raised its full-year revenue forecast from April’s prediction of between $49.5bn and $50.7bn to between  $49.8bn and $51bn, with earnings per share set to rise by 15 cents to between $12.30 and $12.60.

The performance was helped by a $5.6bn “downpayment” the company received from the US Department of Defence earlier this month for F-35s while it negotiates pricing of the jets with the American military.

The F-35 is the biggest ever single defence project, expected to have a price tag of $1.5 trillion over its 50-year lifetime including support.

Britain is a leading participant in the international F-35 programme with the UK military expected to buy about 140 of the jets. BAE Systems is the only tier one partner in the project, with the FTSE 100-listed company building about 15pc of each aircraft.

However, the F-35 has come under intense public scrutiny as costs rise and doubts are raised about the aircraft's performance and abilities.

Earlier this week reports claimed that Britain faced hundreds of millions in “hidden costs” from the jet relating to software upgrades and spare parts, along with claims early models are not performing as advertised.

US President Donald Trump caused the share prices of Lockheed and BAE to dive last year when he tweeted that “based on the tremendous cost and cost overruns of the Lockheed Martin F-35, I have asked Boeing to price-out a comparable F-18 Super Hornet!”.

However, Mr Trump has since reversed his position, saying he had forced Lockheed into price cuts with his original tweet. In a later interview he said that “this was a thing that was out of control and now it's great”.

Despite the criticisms levelled at the F-35, the RAF has been supportive of the fighter, describing it as a game-changing aircraft that will help maintain Britain’s position as a leading military power.