Yemen's prime minister became the first senior politician injured in a June assassination attempt on President Ali Abdullah Saleh to return home from Saudi Arabia, a government official said Tuesday.

The official told Reuters Prime Minister Ali Mohamed Megawar arrived in the capital Sanaa on Tuesday evening and was greeted at the airport by hundreds of government officials and supporters.

Megawar had been receiving medical treatment in Riyadh, along with a number of other presidential aides and Saleh himself, who has repeatedly said he will return to the impoverished Arabian Peninsula state.

Yemen has been paralyzed by months of protests against Saleh's 33-year authoritarian rule.

As violence persisted, the death toll has risen in the south with Islamist militants regularly launching attacks on soldiers, security officials and tribesmen fighting alongside the army.

Four soldiers were killed and some 40 wounded on Tuesday when militants attacked troops stationed south of Zinjibar, the capital of Abyan province, where militants, emboldened by months of upheaval, have taken control of three towns since March.

A security official said two militants were also killed in clashes that broke out on Tuesday and continued into the evening.

Separately, two tribesmen were killed by militants in the coastal town of Shaqra, which they seized last week.

Some tribesmen have sided with the Yemeni army to try to flush militants out of Abyan, setting up checkpoints along roads and last month launching an offensive that has so far failed to recapture much lost ground.

Yemeni warplanes on Monday night killed 5 militants in an airstrike on a checkpoint they had occupied in the al-Arqub area of Abyan, a security official said.

Tribesmen said they saw militants load dead bodies into a car and speed off toward Shaqra.

Residents of Lawdar, another Abyan town, said a suspected suicide bomber driving a motorcycle laden with explosives blew himself up by accident at dawn on Tuesday on the outskirts of the city before reaching his target.

The United States and Saudi Arabia fear that upheaval in Yemen is giving militants, who the government says belong to al-Qaida, more room to launch attacks on the region and beyond.

Opponents of Saleh accuse him of exaggerating the threat of al-Qaida and even encouraging militants in order to illustrate the dangers of Yemen without him and pressure Riyadh and Washington into backing him.

(Reporting by Mohamed Sudam and Mohammed Mukhashaf; Writing by Isabel Coles and Jason Benham; Editing by Maria Golovnina)