Clashes have been reported between protesters and police in Benghazi, Libya's second-largest city.
Witnesses and local media said a crowd angry at the arrest of a rights campaigner clashed with police and government supporters.
The city is reported calm now, but the reports said several hundred protesters armed with stones and petrol bombs had set fire to vehicles and fought with police overnight.
Video clips uploaded overnight on the Internet appear to show groups of protesters in the city chanting slogans.
A local newspaper said 14 people, including 10 police officers, were injured. None of the injuries was serious.
Libyan state media, meanwhile, said rallies in support of Libyan leader Muammar Qaddafi took place in the capital, Tripoli, and several other cities. Qaddafi has ruled the oil-exporting country for four decades.
The government has so far not commented on the developments.
The opposition rally -- a rarity in the autocratic Libyan regime -- comes as political unrest continues to spread through North Africa and Middle East following uprisings in Tunisia and Egypt.
Reports said the Benghazi rally was triggered by the arrest of Fathi Terbil, a lawyer who is an outspoken critic of the government. He was later said to have been freed, but the demonstrations reportedly continued.
In Brussels today, a spokeswoman for EU foreign-policy chief Catherine Ashton, Maja Kocijancic, urged the Libyan authorities to allow "free expression" in the North African country.
"We call on the authorities to listen to all people who take part in protests, as well as what civil society is saying, and to allow free expression," Kocijancic said. "We also call for calm and for all violence to be avoided."Wave Of Unrest
The Libyan protest was part of a wave of antigovernment unrest that has swept through North Africa and the Middle East in recent weeks, forcing the long-serving rulers of Tunisia and Egypt from power.
The antigovernment rallies are being fueled by discontent over unemployment, rising living costs, corruption, and autocratic leaderships.
Family members and supporters of Fadel al-Matrook, a protester who was killed during police clashes, carry his coffin from the mortuary for a funeral in Manama today.
In the last week, protests have taken place in Algeria, Bahrain, Iran, Jordan, and Yemen, where today opponents and supporters of the government clashed for a fourth straight day in the capital, Sanaa.
Government supporter Abdulla al-Nosair spoke to Reuters during a demonstration at Sanaa University, saying, "To the young Arabs and the ones here at the University of Sanaa: We don't believe in what happened in Egypt and Algeria. In Yemen, the regime will not be brought down. It will not be brought down. God's curse on those in the uprising.'"
Reports said police also dispersed protesters demanding President Ali Abdullah Saleh quit in Yemen's main southern city of Aden.
In Bahrain, thousands of antigovernment protesters today gathered at the central Pearl Square in the capital, Manama, maintaining pressure on the government after two days of clashes with police in which two people died.
Hundreds of them earlier attended the funeral of the second Shi’ite victim of the violence, killed at the funeral of the first.
Police appeared to be holding back from altercations after King Hamad bin Isa Al Khalifa addressed the nation on February 15.
The monarch offered condolences for the deaths, pledged an investigation into the killings, and promised to push ahead with reforms that would include loosening state controls on the media and Internet.Talks With The Government
Meanwhile, Interior Minister Sheikh Rashed bin Abdullah al-Khalifa announced that the policemen behind the killing of the two Shi’as had been arrested pending investigation.
The main Shi'ite opposition bloc Wefaq, which boycotted parliament to protest the clampdown by Sunni security forces, said it would hold talks with the government today.
The demonstrators are calling for the resignation of Prime Minister Sheikh Khalifa bin Salman al-Khalifa, who has been in office for 40 years.
Yemeni security forces block antigovernment protesters from advancing during demonstrations on February 15.
They also want the release of political prisoners, more jobs and housing, a more representative and empowered parliament, and a new constitution.
Although 70 percent of Bahrain's population is Shi'ite, the country is ruled by a Sunni Muslim monarchy.
Since independence from Britain in 1971, tensions between the Sunni elite and the Shi'a have frequently caused civil unrest, with Shi'a complaining of being marginalized.
The unrest is a source of worry for the United States, whose 5th Naval Fleet is based in Bahrain. In Washington, the head of a Congressional committee that oversees the U.S. Navy said he had "concern" about the unrest.
Representative Todd Akin (Republican-Missouri), who heads a subcommittee of the House Armed Services Committee, told AFP that Washington was "not quite sure what all of these different destabilized political situations are going to mean" for U.S. relations in the region.
In a statement, U.S. State Department spokesman Philip Crowley called on all parties to exercise restraint.written by Antoine Blua, with agency reports