The world leaders have expressed their condolences to the people and government of Pakistan, condemning "heinous" terrorist acts over a deadly blast in Quetta city in the southwest.

They also stressed the importance of solidarity, vowing to fight against terrorism with Pakistani authorities.

At least 25 people, including women and children, were killed, and 62 others injured in the blast at a railway station in Balochistan Province on Saturday, health and police officials said. The death toll might rise as several injured people have been in a critical condition.

The railways said in a statement that the bombing took place in the morning at Platform No 1 of the station, where the train Jaffar Express was ready to depart.

Pakistan's Prime Minister Shehbaz Sharif condemned the attack and directed the hospital administration to provide the best possible medical treatment to the injured.

United Nations Secretary-General Antonio Guterres strongly condemned the terrorist attack on Saturday, his spokesman Stephane Dujarric said in a statement emailed to the Associated Press of Pakistan.

"The Secretary-General sends his condolences to the families of those killed, as well as to the people and Government of Pakistan. He wishes a speedy recovery to all those injured," the statement said.

Shahid Khaqan Abbasi, former prime minister of Pakistan, told China Daily that this suicide attack is "a despicable act of terrorism".

"Pakistan has been at the forefront of the war against terrorism in the last 30 years, and over 150,000 people, including the armed forces, civil armed forces, police and civilians, have lost their lives," he said.

"Pakistan will continue to use its full force to fight terrorism, and this attack will only serve to reinforce the commitment of the people of Pakistan to defeat terrorism."

Sending condolences to Sharif and Pakistan's President Asif Ali Zardari, Russian President Vladimir Putin described the terrorist acts as a "barbaric crime", adding the culprits should be brought to justice.

"We are determined to continue close cooperation with our Pakistani partners against all forms and manifestations of terrorism," he wrote in a letter.

Malaysian Prime Minister Anwar Ibrahim strongly condemned the violent acts and conveyed his sympathies to the victims and their families.

"Malaysia stands firmly in solidarity with the government of Pakistan in its steadfast fight against terrorism," he wrote on X.

Turkiye's Foreign Ministry said in a letter, "We will continue to support Pakistan in its fight against terrorism."

The proscribed group Balochistan Liberation Army claimed responsibility for the attack in a press release shared with media and on social media platforms.

The military sources from Quetta told Xinhua News Agency that the target of the attack were soldiers leaving for their homes in other provinces after completing their training in Quetta.

They revealed that a suicide bomber blew up his explosive jacket in a crowd of more than 100 people, including soldiers, railway police and civilian passengers.

Immediately after the incident, police, security forces and rescue teams rushed to the site and transferred the bodies and the injured to a hospital. The authorities also started snap checks in various parts of the city with an additional contingent of police and law enforcements deployed for increased security.

Xinhua contributed to this story.