The British Navy has declined Air India's offer to provide a hangar space for its F-35B Lightning II stealth fighter jet, which has been parked in the open in Kerala's Thiruvananthapuram for six days following its emergency landing, media reports said.

The American-origin F-35B is the most expensive fighter jet in terms of programme cost and boasts of advanced technologies that Britain may not want others to take a closer look at, NDTV, quoting sources, reported.

This could be one of the reasons why the Royal Navy declined Air India's offer to move the fighter jet to a hangar space.

It is highly likely that concerns over "protected technologies" may have delayed any decision on the Royal Navy's part to take the F-35B inside a hangar, said reports.

While they have so far declined the offer, they may consider moving it inside the hangar for a final inspection and repair, NDTV's sources said.

The British F-35B Lightning II fighter jet made an emergency landing at Thiruvananthapuram International Airport in Kerala last Saturday night after running low on fuel during a sortie over the Indian Ocean.

"Normal occurence of diversion by F-35. IAF fully aware and facilitated the aircraft for flight safety reasons. All assistance being given, and IAF is in coordination with all agencies," the Indian Air Force had said in a statement.

The 5th-generation stealth fighter is part of the UK's HMS Prince of Wales Carrier Strike Group, which is currently operating in the Indo-Pacific.

The F-35B variant is designed for short take-off and vertical landing (STOVL), which enables it to operate from aircraft carriers without catapult systems.

However, it was not immediately clear why the aircraft was unable to recover onto the Prince of Wales.

As per early indications, poor weather conditions around the carrier may have prevented a safe landing.

The F-35 programme, spearheaded by US defence contractor Lockheed Martin, is considered as one of the most advanced multirole fighter aircraft platforms in service today.

The aircraft's stealth capabilities, electronic warfare systems, and data-sharing infrastructure are of great significance to the US, UK, Israel and NATO's modern air strategy.