The five permanent members of the UN Security Council agreed a draft of new sanctions last week after months of pressure from the United States to punish Iran for nuclear activities that Washington says are aimed at making a bomb.

"In recent days, the issue of sanctions has been raised against our nation. Although we think this situation arose from tactless and adventurous foreign policies, we are against it because it will affect people's lives," Mousavi said in comments carried on his website Kaleme.

Mousavi, who lost to Mahmoud Ahmadinejad in last June's presidential election which the opposition leader says was rigged, said Iran was facing an economic crisis whose full impact has yet to be felt.

A 0.5 percentage point fall in GDP growth last year to 1.8 percent -- according to IMF figures -- was "like undergoing a massive attack by foreign enemies", Mousavi said.

"The pressure of this fall is on entrepreneurs and it will be followed by a heavy unemployment and poverty ... turning back towards the people is the only solution and then you will see that again there is a backdrop of hope," he said.

Some Iran analysts say only major economic hardship could weaken Ahmadinejad's tight grip on power.

The government stamped out massive opposition protests after the election, jailing thousands of people. It said post-election "riots" were backed by foreign powers hoping to unseat it.

Opposition leaders have called on supporters to take part in peaceful election anniversary rallies on June 12.

Later this year, the government will begin phasing out fuel and food subsidies, which may pose an inflation risk and could prove unpopular, although the policy includes dir