The search for two missing pilots in the crash of two RAF in Moray Firth in Scotland is to resume on Wednesday. After the two RAF Tornado GR4s went down on Tuesday, two of the four pilots went missing while two others were later admitted in hospital in Inverness following their rescue by helicopters; their condition has not been disclosed.

The ministry of defence (MOD) confirmed that the search operations were halted on Tuesday night due to bad weather in the region and will be resumed on Wednesday morning.

Reports suggest rescue boats and lifeboat volunteers of the Aberdeen coastguard have also joined the operations.

In a statement released by the MOD, Group Captain Ian Gale, Station Commander RAF Lossiemouth, said this was a "very serious incident" although the exact cause of the accident remains unknown.

There is speculation that the aircraft could have collided in air during the practice.

"The circumstances remain uncertain but clearly this is a very serious incident. I can confirm that two individuals have been recovered and two remain unaccounted for. Rescue operations are continuing and I would like to record my gratitude for the ongoing efforts of all those involved," said Gale.

He said the incident was a stark reminder of the military operations and training undertaken under constant risk.

"This incident involved four aircrew - all personnel from this station - and the thoughts of everyone here are with the families and friends of those involved. As I'm sure you will understand, this is an evolving situation and, as such, I am not prepared to comment at this time on their condition or speculate on the circumstances surrounding this incident," added Gale.

The MoD has promised a full probe into the accident and said it will release further details in due course.

Scotland First Minister Alex Salmond said: "This is clearly a very serious incident and my thoughts are with the loved ones of those affected. I understand rescue services have done all they can to help with the situation and offer my thanks to all those involved," reported the Press Association.

In a similar incident in January 2011, two RAF crew were rescued after a Tornado GR4 went down in the sea near the west coast of Scotland.