TEHRAN Iran on Friday expressed surprise at the UK's fuming over the Islamic Republic's rejection of its proposed ambassador to Tehran, David Reddaway, and London's refusal to name a replacement.

"The reaction of the British Foreign Office to the fact that its proposed ambassador has been rejected is surprising," Foreign Ministry Spokesman, Hamidreza Assefi said.

"Accepting or not accepting an ambassador who is introduced by a country is the natural right of the host country," IRNA quoted him as saying.

"This is not an unprecedented issue. It has repeatedly happened in diplomatic ties of many countries, without undermining their relations," Assefi added.

The Iranian official noted that arrangement of diplomatic ties between two countries is "a reciprocal issue" and countries are "mutually" benefited from their relations.

Foreign Office sources on Thursday were cited as saying the UK had "no plans at present to put forward anyone else" after they announced that Iran had rejected London's choice of Reddaway as new ambassador to Tehran.

Iran in January denied reports of being under duress to accept the accreditation of a new British nominee as ambassador to Tehran.

London has still to name a new ambassador to replace Nicholas Browne who finished his tenure in December.

In 1998, Iran and the UK upgraded their diplomatic ties to ambassador level, with Browne named for the post. He had served as charge d'affaires in Tehran before that.

Ties since then have improved between the Islamic Republic and the United Kingdom. British Foreign Secretary Jack Straw has twice visited Iran in recent months. He was the first figure of that portfolio to visit Tehran since the 1979 Islamic Revolution.