Israel may have to ground its fleet of 140 F-4 Phantom fighter-bombers because Britain has blocked sales of critical spare parts.
Ms Rachel Niedak-Ashkenazi, a spokeswoman for the Israeli Ministry of Defence, she didn't know how soon the planes would have to be grounded, whether in weeks or months. "We are desperately searching for other sources but haven't located any yet," she said.
British government official denied there was an arms embargo, but said exports should not be used against Palestinians.
The Phantom, which has been in Israeli service since 1969, is a US built jet, but uses parts manufactured by Britain's Martin-Baker in the pilots' ejection seats.
In addition to the Phantoms, the Israeli air force has about 350 newer F-15 and F-16 jets - with another 100 F-16s on order. Even without the Phantoms, the air force would remain superior to any potential opponent in the region.
In London, a government official refused to comment on the specific case, but noted that the Foreign Office last year approved 128 export licenses to Israel on military-related items and refused 77.
"There is no official or unofficial embargo on arms exports to Israel but we adhere to our own and European Union criteria which says exports should not be used for internal repression or external aggression," said the official.
"We have to take into account what's happening in the occupied territories."
British government officials have complained in the past that Israel broke a pledge not to use British equipment in its crackdown against the Palestinian Authority. Although Israel's equipment purchases in Britain are not large, they are said to involve a number of critical items.
PA