The Foreign Office summoned Iran's ambassador Friday to complain about remarks by Iran's Supreme Leader Ayatollah Ali Khamenei, who was quoted as calling Britain "the most treacherous" of Iran's enemies.
Britain has been cautious until now in its comments on the Iranian election, not wanting to be seen as interfering in Iran's affairs, but Brown stepped up his criticism Friday.
"We are with others, including the whole of the European Union unanimously today, in condemning the use of violence, in condemning media suppression," Brown told a news conference after a European Union summit in Brussels.
Britain wanted to protect the right of the Iranian people to elect who they wished, Brown said.
"It is for Iran now to show the world that the elections have been fair…that the repression and the brutality that we have seen in these last few days is not something that is going to be repeated," Brown said.
"We want Iran to be part of the international community and not to be isolated. But it is for Iran to prove … that they can respect these basic rights," he said.
Supporters of runner-up Mirhossein Mousavi have held six days of protests since President Mahmoud Ahmadinejad was declared the winner of the Iranian election.
State media have reported seven or eight people killed in the protests. Scores of reformists have been arrested and authorities have cracked down on foreign and domestic media.
Khamenei demanded an end to the protests Friday and denied any possibility that the election had been rigged, as Ahmadinejad's opponents have alleged.
Khamenei attacked what he called interference by foreign powers after the election, singling out Britain for criticism.
The Foreign Office said Rasoul Movahedian, Tehran's envoy to London, had been summoned to meet Mark Lyall Grant, the ministry's political director.
Britain's ambassador in Tehran has been summoned twice by Iranian authorities in the last week to hear complaints about official statements or over British media coverage of the election and protests.
Britain is one of the Western nations that has been most critical of Tehran over its nuclear program. The United States and its allies accuse Iran of trying to develop atomic weapons while Iran says it only wants to generate electricity.
(Reporting by Adrian Croft, Peter Griffiths in London; Editing by Charles Dick)
