Chinook crews from RAF Odiham are now unlikely to be used in a humanitarian mission to help refugees in northern Iraq.
The heavy-lift helicopters would have been used to rescue Yazidi refugees trapped on Mount Sinjar after they fled Islamic State fighters.
A Ministry of Defence (MoD) spokesman said four helicopters arrived in Cyprus in the middle of last week ready for use, if it was decided further humanitarian relief options were needed.
But he said most of the tens of thousands who scrambled up Mount Sinjar to escape advancing militants had now climbed down, so no evacuation rescue was needed.
The spokesman said the Chinooks, which can carry up to 55 people, are still in a pre-position in RAF Akrotiri in Cyprus but it was unlikely they would go any further. From there, they would have moved on and based nearer Iraq.
The US has carried out manned and unmanned air strikes this week while Prime Minister David Cameron has insisted that the UK’s involvement will be limited to providing aid.
Up to 250,000 people have fled the advances of Islamic State fighters in recent weeks.
Iraqi Christians and members of the Yazidi sect have been given an ultimatum to change their religion or die.
A government spokesman said the UK has so far committed £13 million in new assistance in response to the crisis in Iraq.
“We are providing aid to displaced Iraqis currently living in refugee camps across northern Iraq and to the 12,000 Yazidi refugees who have escaped from Mount Sinjar to a refugee camp over the Syrian border,” he added.
On Saturday (August 16), two Airbus flights landed in Erbil carrying UK aid supplies to be distributed by UN agencies to people cut off from their homes in camps across the Dahuk region of northern Iraq.
“There are approximately half a million displaced people in Dahuk - 200,000 since the beginning of August,” added the spokesman. “Those arriving at camps have travelled for days without food and water in 50 degree temperatures.
“In addition, the RAF has made seven successful air drops of UK aid over Mount Sinjar including water containers, solar lamps and shelter kits.”