BBC News with Marion Marshall

The Iranian armed forces say they've shot down an unmannedAmerican spy plane over eastern Iran and will retaliate if there are any further violations of their airspace. They said the stealth plane suffered minor damage and was now in their possession. They identified it as an RQ-170 Sentinel - a radar-evading drone whose secret development and use was only acknowledged by the United States two years ago. Peter Biles reports.

There's been no word from the Pentagon and Washington, but Iran has warned that its response will not be limited to the country's borders.

Earlier this year, Iran said its forces had brought down two US drones that had entered Iran but had produced no evidence. Iran remains in dispute with the West over its nuclear programme although Tehran insists the programme is for peaceful purposes.