Mourners vowed revenge as Libyan leader Moammar Gaddafi’s son Saif al-Arab was buried in the country’s capital Monday, with two of his brothers in attendance, after his death in a NATO airstrike that has raised questions about the alliance’s mission in Libya.

About 2,000 Gaddafi supporters gathered for the funeral, chanting slogans in support of the regime. There was no sign of Gaddafi, who has appeared in public infrequently since NATO warplanes took over Libya’s skies in mid-March.

The chief mourners were Saif al-Arab’s higher-profile elder brothers Mohammed and Saif al-Islam. The latter was once seen as a reformist voice within the government and occasionally tipped as a possible successor to his father.

Saif al-Arab’s coffin, covered in a wreath of flowers and draped in the green flag adopted by the regime since Gaddafi took over in a military coup in 1969, was carried through a throng of supporters, who chanted, “The people want revenge for the martyr” and “Revenge, revenge for you, Libya.”

Soldiers, police officers and bodyguards struggled to corral the crowd as his body was taken to the Hani cemetery, a dusty plot of ground where his grandfather also lies, reportedly killed fighting Italy’s colonial invasion nearly a century ago.

The most recognizable figure at the graveside was the bespectacled Saif al-Islam, dressed in a black round hat, a white shirt and black waistcoast. He reached down to touch his younger brother’s chest for the last time and then fought back tears as the body, covered in a white shroud, was taken from a simple wooden coffin and lowered into the ground.

Swiftly regaining his composure, Saif al-Islam then left the graveside, flashing V-for-victory signs, waving at faces he recognized and shaking his fist in defiance, his every step jostled by a surging and poorly controlled crowd.

The crowd was smaller than might have been expected, given the city’s population of about 2 million and the government’s assertions of strong support for the regime.

Saif al-Arab was killed in a NATO airstrike on his home on Saturday evening, along with a friend and three of Gaddafi’s grandchildren, ages 6 months to 2 years, Libya’s government says. They were the children of Gaddafi’s sons Mohammed and Hannibal and of his daughter, Aisha.

The government says that Gaddafi and his wife were also in the residence at the time of the airstrike but escaped unharmed and that NATO must have had some intelligence about the Libyan leader’s whereabouts, perhaps from an informer or from communications intercepts.

The government’s credibility is so low among its opponents that many people in rebel-held eastern Libya do not believe that Saif al-Arab is dead, suspecting a ploy to divide NATO and undermine its mission. A French orthopedic surgeon, however, said that he had examined the body and compared it to photographs and that it was very probably that of Saif al-Arab.

Anger erupted in Tripoli after news of Saif al-Arab’s death broke, and the U.S., British and Italian embassies were attacked and burnt by mobs that night. In response, Britain expelled the Libyan ambassador to London, while the Libyan government expressed regret and promised to repair the damage.

South Africa, which voted for the U.N. Security Council Resolution authorizing military intervention in Libya but later led an African Union effort to mediate in the conflict, joined in the criticism of the NATO airstrike.

“The attacks on leaders and officials can only result in the escalation of tensions and conflicts on all sides and make future reconciliation difficult,” it said Monday in a statement, declaring that the action went beyond the mandate of the U.N. resolution.

Russia, which abstained in the Security Council vote, also voiced criticism Sunday, calling the airstrike “a disproportionate use of force” and recommending an immediate cease-fire.

Meanwhile, Libyan government forces continued to rain shellfire on the besieged rebel-held city of Misurata and its port Monday.

In a Skype conversation, Mohammad al-Wazzam, a resident of Benghazi who is currently in Misurata, described “heavy fighting and indiscriminate shelling” in multiple districts in the port city, saying that the attacks began at 7 a.m. Monday. “I did not hear any sound of military aircraft flying for NATO to protect civilians,” he added.

In the rebel-controlled eastern city of Benghazi, the opposition Transitional National Council is expected to soon announce its plans for a new state, including key positions in an executive council that would govern until elections can take place.

For the first time, all members of the executive and legislative branches of the council convened for a meeting that began Sunday and continued late into Monday evening.  

Present at the gathering was opposition leader Mahmoud Jibril, a former Gaddafi official.  Jibril has been traveling for several weeks meeting with world leaders.  He is expected to be confirmed as prime minister of the new executive council.

A spokesman for the opposition, Jalal el-Gallal, stressed in an interview that these plans would be for a united Libya and did not represent a new government in the rebel-held east.  “It is inconceivable to have a Libya without Tripoli,” he said.

Special correspondent Portia Walker in Benghazi contributed to this report.