Image caption The planes are based at RAF Waddington in Lincolnshire

Two spy planes due to have been retired at the end of March are now to be kept in service for at least another three months, the BBC has learnt.

The Ministry of Defence has declined to comment on whether the decision is related to discussions on setting up a no-fly zone over Libya.

The Nimrod R1s are sophisticated spy planes currently deployed in the Middle East.

Crews have now been told they will continue in service until June.

The two planes were due to have been officially retired at a ceremony at RAF Waddington in Lincolnshire on 31 March.

But crews at the base have now been told that will not happen and that the planes will continue in service until the end of June at the earliest.

'Think again'

The Ministry of Defence will not comment on the decision beyond saying that in the current circumstances, it is assessing if it might extend the life of what defence experts say are crucial assets.

The UK and France are working on a UN resolution for a no-fly zone in Libya but the US has cautioned that it must be a UN decision with wide international support.

An Ministry of Defence spokesman said: "The Nimrod R1 is due out of service at the end of this month.

"We are assessing if, in the current circumstances, we might like to extend the life of this platform for the short term.

"The original decision to take the R1 out of service was taken in 2008 and is not a result of the Strategic Defence and Security Review."

But the government was accused of a U-turn by Labour.

Shadow defence Secretary Jim Murphy said: "I have been urging the government to stop and think again.

"They should now go the whole way and reopen their rushed defence review."