Iranian human rights activists welcomed the government's decision to free at least 11 political prisoners.

The Committee for the Defence of the Iranian People's Rights (Codir) attributed the release of human rights lawyer Nasrin Sotoudeh and another seven women and three men to long-running pressure by the international community.

Ms Sotoudeh was sentenced to six years in prison in September 2010 for "spreading propaganda against the system" and "acting against national security" - catch-all charges which the government has routinely used to suppress critics of its human rights record.

Codir assistant general secretary Jamshid Ahmadi welcomed news of the prisoner release but stressed that the new leadership's much-trumpeted reformist credentials would depend on more being done to address abuses of human rights.

"Clearly any prisoner release in Iran is to be welcomed but we should be clear that one swallow does not make a summer," said Mr Ahmadi.

"Many more prisoners remain behind bars in Iran, simply for standing up for human rights, women's rights and trade union organisation.

"We still await the release of trade union leader Reza Shabi, student leader Bahareh Hedayat and many others languishing in Iran's jails."

Codir stressed that the release was timed to coincide with President Hassan Rouhani's visit to the United Nations in New York.

"The Iranian regime is not beyond using these prisoner releases for its own purposes," Mr Ahmadi said.

"While we celebrate the release of Nasrin Sotoudeh and others we should take the opportunity to increase the pressure on the regime which has led to their release and press the Iranian government to abolish the policies which give rise to these injustices.

"Codir will continue to work with human rights organisations worldwide to raise awareness of abuses in Iran, seek the release of all political prisoners and press for democratic rights."