TEHRAN Iranian opposition politician Ebrahim Yazdi says the situation for pro-reform activists like himself is getting worse "day by day" in the Islamic Republic.
"Continuously, they are accusing us of soft subversion, accusing us of velvet revolution," the leader of the banned Freedom Movement said in his home in the Iranian capital.
In another part of Tehran, human rights lawyer Nasrin Sotoudeh is also feeling pressure from the authorities. She says she was barred from leaving Iran to receive an Italian award in December and that she is facing court charges over her work.
"I think they want to stop me," Sotoudeh, whose clients include women's rights campaigners, said in her office.
Yazdi and Sotoudeh may be experiencing what one Western diplomat called a "definite clampdown" on dissenting voices, which he said could be due to uncertainty about Iran's June election, the economy and new U.S. President Barack Obama.
"They hate uncertainty and their response to uncertainty is to clamp down, to try to keep the lid on everything, to send warning messages," the Tehran-based diplomat said. "I think that is what we have been seeing in the last few months."
Conservative President Mahmoud Ahmadinejad plans to run for a second four-year term despite criticism from more moderate rivals accusing him of economic mismanagement and of hurting Iran internationally with his fiery anti-Western speeches.
He has set tough terms for any talks with Obama's administration, saying it must change policy not just tactics toward Tehran and apologize for past "crimes" against Iran.
Analysts say the government may also be taking a harder line against activists seeking political and social change because they fear such views will gain ground at a time when Iran is under external pressure over its nuclear plans.
Plunging oil prices could make it more difficult for the world's fourth-largest crude producer to dismiss U.S. and U.N. sanctions over activity the West fears has military aims and also spell trouble for Ahmadinejad's re-election bid, they say.
The diplomat said he did not believe there was widespread dissent in Iran but the authorities "like to control things."
In one high-profile case, the office of Nobel Peace Prize winner Shirin Ebadi's rights group was closed down in late 2008 on the grounds it did not have a permit for its activities.
Women's activist Sussan Tahmasebi suggested the move against Iran's most famous rights advocate sent a signal also to others.
"If she doesn't have immunity it means that none of us have," Tahmasebi said. "It is a big concern to all of us."
Iran rejects Western charges it is violating human rights and says it allows freedom of speech.
Government spokesman Gholamhossein Elham was quoted last week as saying Iranians had "tasted real freedom" after Ahmadinejad came to power in 2005 pledging to revive the values of the 1979 Islamic revolution that ousted the U.S.-backed shah.
But U.S.-based Human Rights Watch said Iran was invoking national security as "a justification for silencing dissent" and that there had been a large rise in arrests of political activists, academics and others last year.
Iran often accuses Western powers of seeking to undermine the Islamic state through a "soft" or "velvet revolution" with the help of intellectuals and others inside the country.
In January, the judiciary said four Iranians had been arrested over a U.S.-backed plot to overthrow the ruling system, in an announcement that analysts said may in part be a warning message to Washington to not interfere in Iran.
In another case that sparked Western concern, Iranian-Canadian blogger Hossein Derakhshan was detained a few months ago and remains in custody.
Canadian media said Derakhshan, who has been nicknamed the "Blogfather" for pioneering a blogging revolution in Iran, was being held on charges of spying for arch-foe Israel.
"Iran continued to use what it calls 'foreign threats' as grounds to suppress civil society," Human Rights Watch said in its latest World Report about the situation in 2008.
Obama has said he sees Iran as a threat but is also offering direct dialogue with its leaders, marking a new U.S. approach from George W. Bush who had sought to isolate Tehran over a nuclear program Tehran says is to generate electricity.
Western diplomats say the change in Washington could offer a rare chance for a thaw in ties severed three decades ago, but that hardliners in Iran could block an opening amid fears that the United States still wants to undermine the Islamic system.
The Bush administration earmarked tens of millions of dollars to foster democracy in Iran, but some Iranian activists have warned this only gave the authorities fresh ammunition against them by portraying them as U.S. agents.
One European diplomat in Tehran said such U.S. policy had been a factor in Iran "tightening the grip on human rights ... on all activists."
Yazdi, a foreign minister in Iran's first government after the Islamic revolution, said police prevented him last month from holding a meeting of 20-30 people in his home in recognition of Ebadi and other human rights activists.
He said the gap between the Iranian people and the authorities was growing. "The deeper it gets the more fearful they become. The more fearful they become, the harsher instrument they use (against) any opposition voices," he said.
Sotoudeh, the human rights lawyer, said she was facing accusations in court including having ties with foreigners and Iranians living abroad but that this would not stop her working.
"It is possible that I'm convicted (and sent) to jail. But I continue," the 45-year-old mother of two said.
(Additional reporting by Edmund Blair; Editing by )