WASHINGTON - Two US Senators have sent letters to President Donald Trump urging to speed up Lockheed Martin's plan to open a production line for the F-16 in India, as well as approve a drone sale to the country.

The letters, written by Senator John Cornyn, a Republican and Mark Warner, a Democrat, were addressed to US Defence Secretary James Mattis and US State Secretary Rex Tillerson.

The first letter calls for the approval of a plan to co-produce F-16 fighter aircraft within India's borders. The second focuses on a pending agreement to export General Atomics-made Guardian unmanned aerial vehicles to the country.

For the F-16 deal, the senators argue it is imperative US-based manufacturer Lockheed Martin secures more production contracts.

"Keeping the F-16 in production will help sustain a fleet of over 1,000 aircraft currently in the Air Force and help preserve thousands of American jobs," the first letter said.

The Indian government is currently deciding between the F-16 and the Saab-made Gripen aircraft. The senators add the competition presents an opportunity to strengthen bilateral ties between the countries. For the pending Reaper export agreement, the authors cite the strategic alliance between India and the United States.

"The security and stability of the Indo-Pacific is a key national security objective of the United States and is bolstered by a strong bilateral defence relationship with India," the senators continued. "Guardian, a non-lethal, maritime surveillance platform provides critical enabling technology and will further our mutual security objectives."