A bomb blast hit a paramilitary convoy on Tuesday in southwest Pakistan, killing four soldiers and wounding 10 others, a government official said.

A separatist group, the Baloch Liberation Army, said in an email sent to Reuters it carried out the attack and said 10 soldiers were killed.

The homemade bomb had been planted along a road in an area about 180 km (113 miles) northeast of Quetta, the capital of southwestern Balochistan province that borders Afghanistan and Iran, Assistant Commissioner Sana Mahjbeen Umrani said.

The paramilitary consists of local recruits headed by officers from Pakistan army.

Ethnic Baloch guerrillas have been fighting for decades for a separate state, saying the central government unfairly exploits regional gas and mineral resources.

The separatists have stepped up attacks in recent months. One of their groups ambushed and laid siege to Pakistan army's two bases in the area last month. Seven soldiers and 13 attackers were killed.

The Baloch insurgents usually attack the army, government officials, gas projects and Chinese interests.

China is involved in developing a deep water port at Gawadar and other projects in the province as part of the China-Pakistan Economic Corridor, which will cost more than $60 billion to develop and which is part of Beijing's Belt and Road initiative.

Islamists militants also operate in the region.

An Islamic State suicide bomber last week blew himself up in the same district as Tuesday's attack, killing seven paramilitary and police personnel.

(Writing by Asif Shahzad; Editing by Edmund Blair)