(CNN) -- Iranian authorities have imposed a virtual information blockade after opposition leaders issued a call for supporters to take to the streets during an important government anniversary on Thursday, people inside the country are saying.
Residents of the Iranian capital said Wednesday that text messages on many messaging services have been blocked and Internet speeds have slowed to a crawl.
The Internet "comes on only a few minutes each day, but you never know when," one Iranian wrote in an e-mail to CNN, which he said took seven hours to send. "This has been going on for more than four days now. I contacted my Internet provider and they said it is out of their control."
The Wall Street Journal reported that the Islamic republic has announced "a permanent suspension of Google's e-mail services," and that a national e-mail service would soon be available. The newspaper's journalist who reported the story said the announcement was first reported on the Web site of the Iranian Labour News Agency -- aligned with former President Mohammad Hashemi Rafsanjani, a reformist -- but the material has since been pulled off the site.
An Iranian tech site -- IT-Iran.com -- on Wednesday published the ILNA story, in which the chief operating officer at the government's information technology company said suspending Gmail "should be seen as an opportunity to guide the nations towards a national based e-mail system. Until we stop putting our trust in foreigners, we will not witness domestic technological progress, which means that we must trust the administration and the system."
"We have heard from users in Iran that they are having trouble accessing Gmail," Google said in a statement to CNN. "We can confirm a sharp drop in traffic and we have looked at our own networks and found that they are working properly.
"Whenever we encounter blocks in our services we try to resolve them as quickly as possibly because we strongly believe that people everywhere should have the ability to communicate freely online. Sadly, sometimes it is not within our control."
While Iranians have reported Gmail services being down for several days, it appeared that Yahoo and other e-mail services were still working late Wednesday. Accustomed to such blocks, Iranians have become savvy about alternative links allowing them to get around government filters so they can communicate via e-mail.
More ominously, human rights groups and opposition Web sites have reported widespread arrests targeting journalists.
According to the Paris-based journalism watchdog Reporters Without Borders, at least eight journalists were arrested Sunday and Monday, bringing the total number of reporters now in prison to at least 65.
"They have arrested everybody," said Nooshabeh Amiri, a journalist who fled Iran five years ago and now writes for the Persian Web site Rooz online from exile in Paris. Amiri said some of her former colleagues are trying to flee Iran.
"Just this morning I helped somebody leave through Iraq," she said.
There were also reports that journalist trying to enter Iran this week have been denied visas by the government. CNN had requested a visa for a correspondent to cover the anniversary events in Iran and that application was denied.
Meanwhile, Iranian security officers have put out a steady drumbeat of warnings, announcing they will not tolerate opposition protesters during state-sponsored celebrations Thursday, the 31st anniversary of the foundation of the Islamic Republic of Iran.
"People's massive participation in 22 Bahman (February 11) rallies will thwart the plots hatched by the enemies to disturb the national ceremony, and enemies will have no opportunity for maneuvering and presenting themselves," Police Chief Brig. Gen. Ahmadi Moqaddam said, according to the state-backed Fars News Agency.
On January 28, authorities executed two opposition activists after convicting them of being "mohareb," or enemies of God.
On Tuesday, a court sentenced another activist to death. At least 10 opposition members now await execution.
"Our phones are strictly followed and controlled," said one young Iranian who participated in past protests, during a phone conversation from Tehran. Speaking on condition of anonymity, the Iranian said that for the first time the satellite television signals in his neighborhood had been jammed.