Da BBC NEWS:
'Three UK vessels seized in Iran'
Iran says it has seized three British navy vessels inside its territorial waters near the Iraqi border.
Eight British sailors on board were arrested when the vessels were seized on the Shatt al-Arab river, state-run Iranian media said.
A spokesman for Iran's Revolutionary Guards said the vessels had entered Iranian waters without permission.
The Ministry of Defence in London confirmed that it had lost contact with three small patrol boats in the area.
At UK military headquarters in Basra, Capt Donald Francis said: "Three small Royal Navy patrol boats and eight crew have been out of communication since the early hours of this morning.
"Their last known location was in the vicinity of the Shatt al-Arab waterway."
Tense relations
The Iranian military spokesman said the boats were being escorted to shore, where an investigation would be conducted.
He indicated they could be freed soon if the inquiry showed there had been no malicious intent.
He said the Revolutionary Guards were now waiting for the Iranian foreign ministry to take up the case.
Iranian naval sources quoted by Iran's official Arab-language al-Alam satellite TV news station said weapons and maps were found on board the vessels.
A spokesman for the UK foreign ministry in London said British diplomats in Tehran were "in close contact" with the Iranian government over the incident.
However, the spokesman said it was still unclear what had happened.
The BBC's Jim Muir in Tehran says relations between Britain and Iran are always delicate and are currently somewhat tense over Iraq, human rights, Iran's nuclear programme and other issues.
But our correspondent adds that incidents of this kind would normally be expected to be resolved in isolation from political complications.