At least four people were killed and a dozen others wounded when a bomb exploded at a top hotel hosting the Chinese ambassador in southwestern Pakistan, officials said late Wednesday.

The blast took place in the car park of the Serena -- a luxury hotel chain throughout Pakistan -- in the city of Quetta, the capital of Balochistan province where the military has been fighting a decade-long low level insurgency.

"At least four people have been killed and 12 others were injured," Pakistan's interior minister Sheikh Rashid Ahmed told AFP, describing it as "an act of terrorism".

"A Chinese delegation of around four people led by the ambassador was lodging in the hotel.

"The ambassador was out for a meeting when the explosion took place," he added.

Balochistan is poor despite its natural resources -- a source of great anger to residents who complain they do not receive a fair share of the gas and mineral wealth.

Resentment has been fuelled by billions of dollars of Chinese money flowing into the region through the China-Pakistan Economic Corridor (CPEC) -- a key part of China's Belt and Road Initiative -- which locals say gave them little benefit as most new jobs went to outsiders.

Azhar Ikram, a senior police official in the city, confirmed the death toll and said that the Chinese ambassador was staying at the hotel, but was not present at the time of the blast.

"Initial probe suggests it was an IED planted in one of the vehicles," Ikram said.

No group immediately claimed the attack.

In 2019 gunmen stormed a luxury hotel overlooking a flagship CPEC project -- the deep-water seaport in Gwadar that gives China strategic access to the Arabian Sea -- killing at least eight people.

And in June, Baloch insurgents targeted the Pakistan Stock Exchange, which is partly owned by Chinese companies.

All the attacks were claimed by the Balochistan Liberation Army.

It comes after more than a week of violent anti-France protests led by an extremist party based in the eastern city of Lahore.