At least three paramilitary troops were killed and 20 others injured in a suicide attack in Pakistan's restive Balochistan province on Sunday, media reports said.

The outlawed Tehreek-e-Taliban Pakistan (TTP) claimed responsibility for the attack, Dawn newspaper reported.

The explosion took place near a checkpost of the Frontier Corps (FC) on the Quetta-Mastung highway, Deputy Inspector General of Quetta police Azhar Akram said.

Eighteen of the injured were security officials while two were bystanders, the officer said, adding that the number of casualties could rise.

According to the Counter-Terrorism Department Balochistan's spokesperson, the blast was a "suicide attack" and was carried out near the Sona Khan checkpost.

The report said that three personnel of the Frontier Corps were killed in the attack.

Prime Minister Imran Khan took to Twitter to condemn the attack.

Condemn the TTP suicide attack on FC checkpost, Mastung road, Quetta. My condolences go to the families of the martyrs & prayers for the recovery of the injured. Salute our security forces & their sacrifices to keep us safe by thwarting foreign-backed terrorists' designs, he said in a tweet.

Balochistan Home Minister Mir Ziaullah Langove also condemned the attack and sought a report.

"Security forces have given countless sacrifices in the war against terrorism. The whole nation is indebted to the martyrs. We are fighting the terrorists with our full strength and will continue to do so. These violent attacks will not lower the morale of the forces," he said, adding that the war would continue until total peace was achieved.