Libyan leader Muammar Gaddafi is fighting to hang on to power after anti-government protests spread to the capital Tripoli from the country's east.
Among demonstrators' demands are an end to human rights abuses that critics say have marked his 41-year-old rule.
The government denies it routinely abuses its citizens but Saif al-Islam Gaddafi, one of his sons, has said the government has been responsible for some human rights failings in the past.
Following are examples of reported abuse, torture and killings by the state since Gaddafi took power on September 1, 1969.
1970s - ARRESTS, TELEVISED HANGINGS
Rights groups and Gaddafi's foes say that throughout the 1970s police and security forces arrested hundreds of Libyans who opposed, or who the authorities feared could oppose, his rule.
Student demonstrations were put down violently. Political opponents were arrested and imprisoned, or simply disappeared.
Police and security forces rounded up academics, lawyers, students, journalists, Trotskyists, communists, members of the Muslim Brotherhood and others considered "enemies of the revolution," Human Rights Watch says. Gaddafi warned anyone who tried to organize politically they would face repression.
"I could at any moment send them to the People's Court ... and the People's Court will issue a sentence of death based on this law, because execution is the fate of anyone who forms a political party," Gaddafi said in a speech on November 9, 1974.
A number of televised public hangings and mutilations of political opponents followed, rights groups say.
In 1976 Gaddafi authorized the execution of 22 officers who had participated in an attempted coup the previous year, in addition to the execution of several civilians, rights activist Mohamed Eljahmi has written.
1980s: DETENTION, DISAPPEARANCES
In 1980 authorities introduced a policy of extrajudicial executions of political opponents abroad, termed "stray dogs."
According to a 2009 article in Forbes magazine by rights activist Eljahmi, Gaddafi's then deputy Abdel Salam Jalloud issued a public justification in 1980 for the assassination of dissidents abroad, telling Italian media:
"Many people who fled abroad took with them goods belonging to the Libyan people ... Now they are putting their illicit gains at the disposal of the opposition led by (then Egyptian leader Anwar) Sadat, world imperialism, and Israel."
A failed coup attempt in May 1984 apparently mounted by exiles with internal support led to the imprisonment of thousands of people. An unknown number of people were executed.
In 1988 there was a period which appeared to herald important human rights reforms. Authorities freed hundreds of political prisoners in a wide-ranging amnesty.
But more repression ensued in 1989. According to Amnesty International, which had visited the country in 1988, the government instituted "mass arbitrary arrest and detention, "disappearances,' torture, and the death penalty."
One of the main causes of the crackdown was the return to Libya of Libyan citizens from Afghanistan, where they had gone to fight Soviet forces. Some returned home with hopes of overthrowing Gaddafi and installing Islamic rule.
1990s: MASS KILLING AT PRISON
In 1993, after a failed coup attempt in which senior army officers were implicated, Gaddafi began to purge the military periodically, eliminating potential rivals and replacing them with loyalists.
In what critics call probably the bloodiest act of internal repression, more than 1,000 prisoners were shot dead by security forces on June 28 and 29, 1996 in Abu Salim prison, according to Human Rights Watch.
The scale of the killings was confirmed by the Libyan Secretary of Justice to Human Rights Watch in April 2009, and in a press release by Saif al-Islam's Gaddafi Foundation charity on August 10, 2009 which set the number at 1,167.
For years Libyan officials denied that the killings at Abu Salim had ever taken place. The first public acknowledgement was in April 2004 when Gaddafi said killings had taken place there, and that prisoners' families had the right to know what took place. To date there has been no official account of the events at Abu Salim prison.
2000s: MAN FREED -- AFTER 31 YEARS
Rights groups say the authorities have taken limited steps to address the situation, including releasing some political prisoners and allowing infrequent visits by rights groups.
In 2001 nearly 300 prisoners, among them political prisoners, were released. They included Libya's longest-serving political prisoner, Ahmad Zubayr Ahmad al-Sanussi, accused of involvement in an attempted coup in 1970 and who spent 31 years in prison, many of them in solitary confinement.
More than 700 prisoners accused of having ties to Islamist militant groups have been released in the past three years under a reconciliation program organized by the Gaddafi Foundation.
(Sources: Human Rights Watch, Amnesty International, U.S. State Department, Libyan political scientist Mansour Kikhia, Mohamed Eljahmi, co-founder of the American Libyan Freedom Alliance, Reuters)
(Editing by David Stamp)