Gunmen in south-western Pakistan killed at least 31 people in two separate attacks on Monday, with reports of other shootings and unrest across the same province, police and officials said.

Twenty-three people were fatally shot after being identified and taken from buses, vehicles and trucks in Musakhail, a district in Baluchistan province, senior police official Ayub Achakzai said.

The attackers burned at least 10 vehicles before fleeing.

In a separate attack, gunmen killed at least nine people, including four police officers and five passers-by, in Qalat district also in Baluchistan, authorities said.

Insurgents blew up a railway track in Bolan, attacked a police station in Mastung and attacked and burned vehicles in Gwadar, all districts in Baluchistan.

No casualties were reported in those attacks.

Baluchistan has been the scene of a long-running insurgency in Pakistan, with an array of separatist groups staging attacks, mainly on security forces.

The separatists have been demanding independence from the central government in Islamabad.

Although Pakistani authorities say they have quelled the insurgency, violence in Baluchistan has persisted.

The attack in Musakhail came hours after the outlawed Baluch Liberation Army (BLA) separatist group warned people to stay away from highways as they launched attacks on security forces in various parts of the province. But there there was no immediate claim of responsibility for the latest killings.

Separatists often ask people for their ID cards, and then abduct or kill those who are from outside the province. Many recent victims have come from neighbouring Punjab province.

Uzma Bukhari, a spokeswoman for the Punjab provincial government, denounced the latest killings on Monday, saying the “attacks are a matter of grave concern” and urging the Baluchistan provincial government to “step up efforts to eliminate BLA terrorists”.

Pakistan Interior Minister Mohsin Naqvi said security forces in Baluchistan had responded to the latest attacks, killing 12 insurgents.

He said authorities will reveal who was behind the latest attacks after completing an investigation, but noted that “terrorists and their facilitators will have no place to hide” in the country.

Pakistani President Asif Ali Zardari and Mr Naqvi in separate statements called the attack in Musakhail “barbaric” and vowed that those behind it will not escape justice.

Later, Mr Naqvi also condemned the killings in Qalat.

In May, gunmen fatally shot seven barbers in Gwadar, a port city in Baluchistan.

In April, separatists killed nine people after abducting them from a bus on a highway in Baluchistan, and the attackers also killed two people and wounded six in another car they forced to stop. BLA claimed responsibility for those attacks at the time.

Syed Muhammad Ali, an Islamabad-based security analyst, said the latest killings of non-Baluch people are an attempt by separatists to harm the province economically.

He told the Associated Press that most such attacks are carried out with the aim of economically weakening Baluchistan, noting that “the weakening of Baluchistan means the weakening of Pakistan”.

He said insurgent attacks could hamper development work being done in the province.

Separatists in Baluchistan have often killed workers and others from the country’s eastern Punjab region as part of a campaign to force them to leave the province, which for years has experienced a low-level insurgency.

Most such previous killings have been blamed on the outlawed group and others demanding independence from the central government in Islamabad. Islamic militants also have a presence in the province.

In a separate attack on Monday, in north-western Khyber Pakhtunkhwa province, a roadside bomb killed four people and injured 12 others in North Waziristan district, said local administration official Abid Khan.