Tripoli (Libya): Ahead of planned anti-government protests on Friday, fighters loyal to Muammar Gaddafi set up checkpoints in Tripoli, raising fears of new bloodshed in the Libyan capital where a heavy crackdown past week has spread fear among residents.

The opposition has called for protesters to march out of mosques after noon prayers in demonstrations demanding Gaddafi's ouster. Similar protests last Friday were met with brutal retaliation. Pro-regime militiamen opened fire immediately on the marches, killing and wounding a still unknown number.

Internet services, which have been spotty throughout Libya's upheaval, appeared to be halted completely in Tripoli on Friday, as well as in Benghazi, the opposition's stronghold in the east. The extent of the cutoff was not clear. Also, Libyan authorities barred many foreign journalists from leaving their hotel in Tripoli, claiming it was for their protection because they had information "al-Qaida elements" plan to open fire on police to spark clashes.

Several hours before prayers, streets were eerily empty, with few residents out. Security forces, however, began to take up positions.

In Tajoura, an eastern district of the capital where protests a week ago were attacked, police set up two checkpoints on the main highway leading to downtown. They stopped cars to search them, check drivers' ID and ask where they were going or coming from. Another police car was set up not far from the district's main Murad Agha Mosque.

Friday could be a significant test of whether the opposition can maintain protests in Tripoli in the face of a fearsome clampdown. The capital is crucial to the Libyan leader, his strongest remaining bastion, after the uprising that began on Feb. 15 broke the entire eastern half of Libya out of his control and even swept over some cities in the west near Tripoli.

The crisis has turned into something of deadlock between the two sides. Gaddafi's forces have been unable to take back significant ground from the rebellion, which has repelled repeated attacks on several opposition-held cities. At the same time, his opponents, made up of ragtag citizen militias backed by mutinous army units, don't seem to have the capabilities to make a military move against territory still in regime hands.

Instead, the eastern-based opposition is hoping that residents of those areas — including Tripoli — will be able to rise up like they did in other cities where protesters drove out Gaddafi loyalists.

Gaddafi loyalists have been working to make sure that doesn't happen in the capital by unleashing a wave of arrests and disappearances since last Friday's bloodshed. Bodies of people who vanished have been dumped in the street. Gunmen in SUVs have descended on homes in the night to drag away suspected protesters, identified by video footage of protests that militiamen have pored through to spot faces. Other militiamen have searched hospitals for wounded to take away.

Residents say they are under the watchful eyes of a variety of Gaddafi militias prowling the streets. They go under numerous names, Internal Security, the Central Support Force, the People's Force, the People's Guards and the Brigade of Mohammed al-Magarif, the head of Gaddafi's personal guard, and they are all searching for suspected protesters.

The fear among Gaddafi opponents is so intense that when one family set up a mourning tent in Tripoli's Fashloum neighborhood on Thursday for a 56-year-old protester killed last Friday, no one showed up to pay condolences.