Six RAF Harrier GR7 jets are to stay longer in Afghanistan to support UK troops and their allies on the ground.
The Harriers will now stay until 31 March 2007
The planes had been due to end their deployment in June but will continue until the end of March next year after calls from Nato and coalition chiefs.
As he visited UK troops in Afghanistan, Defence Secretary John Reid said the Harriers were "an essential tool".
They would provide reconnaissance and air support to ground troops under fire from insurgents, he said.
Under the original plans, the Dutch forces was due to provide air support for coalition grounds forces in Afghanistan.
But Mr Reid said some chiefs of staff who reviewed the force requirements had asked for the deployment to be extended.
'Show of force'
The jets have been in Afghanistan since September 2004.
One of their key roles has been to try to deter insurgents by providing a "show of force" by flying low and fast over "hot spots".
Mr Reid said: "The Harriers will continue to provide a reconnaissance capability, an air presence to reassure the Afghan people of their security and the capacity to strike against insurgents that may threaten the safety of our Armed Forces and those under their protection."
The planes are from No 1 Squadron based at RAF Cottesmore. They are working from Kandahar airbase.
Mr Reid is visiting some of the 3,300 sent to volatile Helmand in southern Afghanistan.
The troops are meant to focus on helping reconstruction work but Mr Reid said they might be used at times to seek out and kill Taleban and al-Qaeda terrorists.
Conservative shadow defence secretary Liam Fox welcomed the government's change of mind about the Harriers.
"We have called from the outset for these air assets to remain in place past June this year," said Dr Fox.
"With the build up of more British troops in Southern Afghanistan it would have been irresponsible to withdraw the Harriers just as our troops arrive."