LONDON (Reuters) - Britain denied interfering in Iran's internal affairs on Monday and said it would be regrettable if Tehran downgraded its relations with London.

The Foreign Office published an open letter from Britain's Ambassador to Tehran, Simon Gass, to a senior Iranian member of parliament in response to recent calls by some Iranian parliamentarians to cut ties with Britain.
Iranian officials have repeatedly accused Western powers, including Britain, of fomenting street protests that erupted after the Islamic Republic's presidential election last June.
Britain is pushing for tougher sanctions against Iran over its nuclear program, which Iran says is peaceful.
In the letter to Alaeddin Boroujerdi, chairman of the Iranian parliament's foreign policy and national security commission, Gass said any decision by parliament to downgrade relations with Britain “would be regrettable.”
Gass said it was “entirely untrue” that Britain or its embassy in Tehran were interfering in Iran's domestic affairs.
Iranian media reported last month that dozens of Iranian members of parliament had proposed cutting relations with Britain. ISNA quoted Boroujerdi at the time as saying the proposal was hasty.
In late December, Iran summoned Gass and Foreign Minister Manouchehr Mottaki threatened Britain with a “slap in the mouth” if it did not stop interfering in Iranian affairs.
Even if the parliament voted to cut or scale back relations with Britain, such a move must be approved by a powerful legislative body, the Guardian Council.
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