The Muslim Brotherhood, Egypt's largest opposition group, joined on Tuesday the campaign for a general strike against the government on May 4, the 80th birthday of long-serving president Hosni Mubarak.
Brotherhood leader Mohamed Mahdi Akef said people should stay at home "in peaceful protest to demand solutions to the crises and to tackle the deteriorating conditions which the people are suffering".
"The Muslim Brotherhood is against public policies which entrench corruption and despotism... The executive has blocked its ears and shut its eyes to all calls for reform," he added.
Resentment against the government has grown in recent months, driven by the arrest and trial of Brotherhood members and the rising cost of food hitting hard in a population suffering widespread poverty.
A group of activists, mainly leftists and liberals, agitated for a national strike on April 6 to coincide with a strike by textile workers in the Nile Delta town of Mahalla al-Kubra, without much success outside the town itself.
The Brotherhood, which can mobilize larger crowds than any other opposition force in Egypt, did not actively back that strike, depriving the protest movement of crucial support.
Advocates of a May 4 strike, grouped on the social networking site Facebook, are demanding a minimum wage, salary rises linked to inflation, legislation and other measures to control prices, and the release of people detained in Mahalla.
The main Facebook group promoting the strike now has close to 74,000 members, up from about 60,000 a month ago.
The May 4 strike also has the support of the umbrella protest movement Kefaya, which began in 2004 in opposition to a new presidential term for Mubarak or any attempt to install his politician son Gamal as his successor.
Mubarak, the fifth oldest executive head of state in the world, has been in power since 1981, when he became president on the assassination of President Anwar Sadat.
His current fifth term expires in 2011 and he has not said what he intends to do afterwards. His son Gamal, a senior official of the ruling party, has denied having any presidential ambitions but is widely seen as Mubarak's obvious heir.
Issandr el-Amrani, an analyst at the International Crisis Group, said it was natural for the Brotherhood to take a more confrontational attitude toward the government after a military court jailed 25 members on April 15.
"But I don't really see that this strike in itself, even if the Muslim Brotherhood supports it, is going to be a decisive moment," Amrani said.
Two people were killed and more than 150 injured in the Mahalla riots held over two days earlier this month. People tore down pictures of Mubarak and attacked riot police sent to deter the strike.
The government, on the defensive after recent big jumps in food prices, quickly offered the Mahalla workers more money. Prime Minister Ahmed Nazif has promised that public-sector workers will get pay rises of at least 20 percent in July.