Brahmi funeral
Mourners carry the coffin of Tunisia's assassinated opposition leader Mohamed Brahmi, who was shot dead in a drive-by killing

Thousands of mourners chanted anti-government slogans at the state funeral of the assassinated Tunisian opposition leader Mohamed Brahmi, who was shot dead on Thursday in a drive-by killing in the capital, Tunis.

Relatives and supporters of Brahmi accused the ruling Islamist Ennahda party of complicity in his murder.

Tunisian interior minister Lotfi Ben Jeddou refuted the accusation, instead accusing the weapons smuggler and Salafist militant Boubakr Hakim of Brahmi's murder. He even claimed the two leaders were shot dead with the same gun.

Earlier in the day, a policeman was reportedly injured when a car bomb exploded outside a police station in the city, further destabilising the situation in a country previously regarded as a model in the region's transition to democracy.

Mohammed Brahmi's coffin was carried by soldiers to Jellaz cemetery and buried beside the grave of Chokri Belaid, the opposition leader murdered in February.

Brahmi's widow and five children led the coffin on its route, accompanied by the army chief of staff, Gen Mohamed Salah Hamdi.

"The people demand the fall of the regime! Down with the party of the Brotherhood!" the mourners chanted, in a reference to the Ennahda Party's affiliation with the region-wide Muslim Brotherhood movement, whose leader in Egypt, Mohamed Morsi, was deposed in a coup, sparking widespread violence.

Tunisia's opposition is demanding the dissolution of the government, blaming it for failing to rein in Islamist extremists, turn around the economy or manage the transition to democracy.

Speaking by the graveside, lawyer and activist Nacer Laouini called on Gen Hamdi to protect the people from the Islamists, in a clear reference to the military coup in Egypt against the elected government of Morsi.

"The head of the army is here. We ask the army to be on the side of the people as it always has been and protect Tunisians against Ennahda," he said.

However, turnout fell far short of the hundreds of thousands that came for Belaid's funeral in February. Tunisia's army has had little involvement in politics, unlike in Egypt.

A 48-year-old political activist in Brahmi's leftist coalition died on Friday after being hit in the head by a tear gas canister at a rally in the southern town of Gafsa.

Brahmi, 58, the leader of the nationalist Movement of the People party, was killed by gunmen on a motorbike as he sat in his car on Thursday.

The interior ministry alleged Hakim shot Brahmi 14 times outside his home on Thursday in full view of his family with the same 9mm semi-automatic handgun used to kill Belaid, before he sped away on the back of a moped.

Hakim was a member of the cell that murdered Belaid in February. The killing sparked mass protests and led to the resignation of the prime minister, Hamadi Jebali.

Six opposition parties have now withdrawn from the national assembly and called for the Islamist-led government to be replaced by a national unity administration.

Brahmi, a socialist and practising Muslim with a pan-Arab ideology, was less prominent than Belaid, and less vocal an opponent of Ennahda, which won elections that followed the January 2011 uprising.