WASHINGTON: Lockheed Martin Corp is using its own funds to pay suppliers and stave off the closure of its F-16 fighter jet production line as it waits to finalise orders from Pakistan and other countries, a company official said on Tuesday.

Orlando Carvalho, who heads Lockheed's Aeronautics division, said the cost of keeping the F-16 supply chain ready for further orders was "very manageable", but did not elaborate.

"We will have a gap in the production line because of the fact that there hasn't been another order yet," Carvalho told Reuters in an interview at the company's annual media day.

Lockheed is now funding suppliers to ensure it will be able to build planes for Pakistan and other countries after it wraps up work on 36 F-16 jets ordered by Iraq in 2017.

Congress and the United States (US) State Department are in talks about funding for a $700 million sale of eight F-16 fighter jets to Pakistan that were approved by Congress last week.

The US Senate last week blocked a bid to derail the sale, but Senate Foreign Relations Committee Chairman Bob Corker has vowed to block the use of US funds to finance the deal.

Corker and other lawmakers have expressed concern about Pakistan's nuclear program, commitment to fighting terrorism and cooperation in the Afghanistan peace process.

Other lawmakers and State Department officials support the sale, saying the South Asian state needs to modernise its air force and counter-terrorism activities.

The US named Pakistan as a key partner in its war against terror following the Sept 11, 2001, attacks and spent billions of dollars on military aid to help the country fight insurgents.

But there is growing concern in Washington about providing the same level of assistance to Pakistan unless it shows it is using the funds effectively to eliminate militants.

Carvalho deferred questions about the Pakistan sale to the US government, which is overseeing the deal. Bahrain, Colombia and Indonesia have also expressed interest in F-16 fighter jet orders, and other countries could follow in later years, Carvalho said.

He said Lockheed was working with the US government, which is in talks with India about possibly building F-16s in India.

Susan Ouzts, vice president of Lockheed's F-16 program, told reporters that Indian Prime Minister Narendra Modi had expressed "substantial" interest in the plane during a recent meeting with Lockheed. She said Lockheed officials would travel to India next month with a formal offer.