The euphoria of the Arab Spring has given way to abuses as new governments fail to respect freedom of expression and other basic rights, Human Rights Watch warned in its annual report Thursday.

The U.S.-based group urged the fledgling regimes of countries such as Egypt, Libya and Tunisia to build "genuine" democracies, saying that even democratically-elected governments did not have a mandate to ignore human rights.

British Prime Minister David Cameron flew into the Libyan capital on Thursday for a previously unannounced visit, an Agence France Presse photographer in Tripoli reported.

Cameron, whose visit comes only a few days after Britain warned of threats to its embassy in Tripoli, arrived at Tripoli airport at 11:00 am (10:00 GMT), amid tight security.

There are still 200,000 armed fighters in "revolutionary brigades" in Libya, a top U.N. envoy said Tuesday, expressing fears that Mali's conflict could spillover into the country.

Foreign governments have raised concerns about security in Libya and U.N. envoy to the country Tarek Mitri said France's military campaign in Mali had opponents in Libya.

A Muslim Brotherhood official and member of the local council from Misrata shot dead as he left a mosque in the Libyan city, a local source told Agence France Presse on Sunday.

"Sheikh Mohamed bin Othman was shot dead as he left a mosque after prayers" on Saturday, the source said on the condition of anonymity.

France on Friday joined Britain, other European states and Australia in pulling its nationals out of Benghazi because of a terrorist threat that the Libyan government has played down.

Having insisted Thursday there was no "no new intelligence" to justify the Europeans' concerns, Libya said Friday it had not been informed of their plans to pull citizens out of the country's second city and was seeking clarification from Britain.

Britain, Germany, the Netherlands and Australia have all urged their citizens to leave the Libyan city of Benghazi due to a "specific, imminent threat to Westerners,” linked to French action in Mali.

Britain's warning Thursday sparked an angry response from Libya's government, which said there was "no new intelligence" to justify such concerns in the eastern city.

Almost 150 people, mostly children, were injured by fireworks in Tripoli set off to celebrate the Prophet Mohammed's birthday, hospital sources said on Thursday.

"On Wednesday night we received more than 120 victims, mostly children, who suffered from burns of varying degrees," news agency LANA quoted Bashir al-Shawess of Tripoli's burns hospital as saying.

Libya's former rebels from the town of Zintan on Thursday denied an Algiers newspaper report of having sold arms to Islamists who seized an Algerian gas plant last week.

"We deny the information published by the Algerian newspaper Echorouk accusing Zintan revolutionaries of having sold weapons used by terrorists" at the In Amenas plant, said the military council of Zintan, southwest of Tripoli.

Britain, Germany and the Netherlands urged their citizens on Thursday to immediately leave Benghazi after London warned of a "specific and imminent threat to Westerners" in the eastern Libyan city.

Britain's warning sparked an angry response from Libya's government, which said there was "no new intelligence" to justify such concerns in the city which was the cradle of the uprising that ousted strongman Moammar Gadhafi in 2011.

French air raids on the fabled Malian city of Timbuktu destroyed a mansion belonging to Libya's former strongman Moammar Gadhafi which was being used by Islamist radicals as their headquarters, officials said.

French planes bombed a major base of the al-Qaida in Islamic Maghreb (AQIM) near Timbuktu, a French defense ministry official confirmed on Tuesday, speaking on condition of anonymity. The last raids took place on Sunday night.