Quetta - Bombings killed at least 43 people in three different areas of Pakistan on Sunday, just as Britain's prime minister was in the capital pledging to help to fight extremism.
In the deadliest of the attacks, twin blasts near a Shi'ite Muslim mosque in Quetta killed at least 22 people and wounded 65 others, said a senior police officer.
Initial reports indicated a hand grenade the first blast, forcing people to run in the direction of the mosque, where a suicide bomber detonated his explosives.
Radical Sunni Muslims have stepped up attacks in the past two years against minority Shi'ites, whom they consider to be heretics.
Local TV video showed ambulances rushing victims to the hospital and wheeling them inside on stretchers. Some of the bodies were covered with white sheets. Relatives of the victims frantically entered the emergency room to inquire about their loved ones.
British Prime Minister David Cameron told his Pakistani counterpart, Nawaz Sharif, that Britain would do all it can to help fight extremism, a battle that he said requires both a tough security response and measures to fight poverty and promote education.
"The enemies of Pakistan are enemies of Britain, and we will stand together and conduct this fight against extremism and terrorism together," Cameron said at a joint news conference with Sharif in the Pakistani capital, Islamabad.
Cameron arrived in Pakistan following a visit to neighbouring Afghanistan. He welcomed Pakistan's stated commitment to help promote a peace deal with the Afghan Taliban.
Pakistan is seen as key to any deal because of its historical links with the insurgents.
Pakistan pushed the Taliban to carry through with its recent step to set up a political office in the Gulf country of Qatar, although acrimony between the insurgents and the Afghan government has hampered the negotiation process.