Relations between Tehran and London have deteriorated sharply in recent weeks over British efforts to refer Iran's nuclear case to the U.N. Security Council. British officials have also accused Iran of aiding insurgents operating in Iraq.

Iran, in turn, has accused Britain of helping Arab separatists carry out attacks in its southwestern Khuzestan province, the heart of Iran's oil industry, where a number of small bombings and ethnic protests have taken place this year.

Two homemade bombs placed in garbage bins and detonated three minutes apart killed four people and injured more than 80 in Khuzestan's capital Ahvaz on Saturday.

The British embassy in Tehran issued a statement on Sunday condemning the blasts.

"There has been speculation in the past about alleged British involvement in Khuzestan," the statement said.

"We reject these allegations. Any linkage between the British government and these terrorist outrages is certainly without foundation," it said.

Asked about British involvement in the bombings, Iran's foreign ministry said the matter was under investigation.

"Unlike the British we are not going to express our views without the necessary investigations," spokesman Hamid Reza Asefi told a weekly news conference on Sunday.

"We don't talk without proof and documentation," he said, in reference to Tehran's complaints that London not provided evidence to support its accusations about Iran's alleged involvement in Iraq.

Iran's hardline state media was eager to point the finger of blame at Britain.

"It has to be noted that Ahvaz has previously witnessed such blasts and investigations proved that British troops in Iraq were involved in these," the state-run Al-Alam Arabic news network said.

Many agree on the streets of Iran, where mistrust of Britain typically runs high.

"Who else could it have been but the British?" an unidentified man asked on state television as he was interviewed close to the site of Saturday's blasts in Ahvaz.