The crackdown in the foreign press in Iran has intensified significantly today. This morning, foreign reporters were barred from covering protests. Now ABC News' Jim Sciutto says via Twitter that he's not allowed to leave his hotel.

"Not allowed to leave the hotel, but I think I can see small# of protesters on Vanak Sq," wrote Sciutto about a half-hour ago. CNN's Reza Sayah has been on the streets, but explaining to viewers that he's not being allowed to broadcast any footage from rallies. UPDATE: A CNN spokeswoman says Sayah's "credentials limit his movement to the proximity of the workspace (the hotel) and the surrounding area."

According to an ABC News spokesman, Sciutto was warned by Iranian authorities earlier this week that his permit to operate in the streets had been revoked by Iranian authorities, but his team ignored the threat.

UPDATE: An ABC News spokeswoman says that Sciutto is not physically barred from leaving the hotel, but that his credentials prevent him from doing any work outside of it: "He's not supposed to work outside of the hotel—film, attend protests, do interviews, etc." But he could go out for a bite to eat if he wanted to. The spokeswoman says keeping Sciutto from leaving the hotel was ABC News' idea: "Jim was out this morning, but once the new regulations were announced, we thought it best for him to stay closer to the hotel." Sciutto has updated his Twitter feed to clarify, writing, "In ans. to some q's, we're not confined to our hotel, but barred from working outside."

An NBC News spokeswoman says that NBC News crews have not, to her knowledge, been confined to their hotel.

The New York Times' Bill Keller, who left the editor's desk to report from Iran last weekend and is still in the country, told Editor & Publisher via e-mail that his movements in the country are being closely monitored:

the iranians watch us closely, seem to know where we are much of the time. yesterday i took a five-hour drive to isfahan, in western iran (details TK in the nyt) and on the way we stopped to take a peek at the holy city of qom. as we were making a loop through that city, my translator got a call on his cell phone from the ministry that oversees the press: "please tell me, what is your program in qom.'

Keller's visa is up tomorrow, and as various reporters' visas expire, they're faced with a difficult choice:

some reporters have contemplated overstaying their visas, trying to work under the radar. even if you manage to elude the authorities, though, you create real dangers for all the iranians you would need to hide you, translate for you, get you around and help you get the story out.

UPDATE: Reuters reporters are confined to their offices. The service is adding an editor's note to dispatches from Tehran: "Reuters coverage is now subject to an Iranian ban on foreign media leaving the office to report, film or take pictures in Tehran." And the Associated Press' latest dispatch likewise contains this paragraph:

The report could not be independently confirmed due to the media restrictions barring reporters for foreign organizations from reporting outside their offices.