ISTANBUL

China on Sunday expressed "deep shock" over a recent suicide bombing at a mosque in Pakistan, pledging support to its longtime ally against terrorism.

"China is deeply shocked by the deadly explosion in Pakistan’s capital Islamabad and the heavy casualties it has inflicted," a Chinese Foreign Ministry spokesperson said in a statement.

Beijing said it "strongly condemns the attack, opposes any form of terrorism and firmly supports the Pakistani government in safeguarding national security and stability and protecting the safety of the people."

Some 31 people were killed and 169 injured when a suspected suicide bomber blew himself up at a Shia mosque during Friday prayer.

Islamabad said it has arrested four facilitators, including the Afghan ISIS mastermind behind the attack.

Interior Minister Mohsin Naqvi said "terrorist organizations are operating from Afghanistan," and accused India of providing them with financial support.

Both India and Afghanistan have denied any involvement in the attack.

The Friday suicide bombing was the second major attack in Islamabad in less than three months.