Islamic State in Iraq and Syria (Isis) has claimed responsibility for a suicide bomb attack on a Shia mosque in the Eastern Province of Saudi Arabia.

The 22 May blast at the Imam Ali mosque in Al-Qadeeh, in Qatif governorate, killed at least 21 people and left 80 injured.

According to reports, Isis affiliate Wilayat Najd posted an image of the bomber before the blast on social media website Twitter. Najd is the central region of the kingdom and includes Riyadh, Al-Qassim, and Hail.

The attack could heighten tensions in the Eastern Province which is home to the majority of Saudi Arabia’s Shia population.

The province is also close to the island of Bahrain, which faced a Shia uprising that was quickly put down with Saudi military support in 2011.

Saudi Arabia is also leading military operations against Houthi rebels that adhere to the Zaidi sect of Shia Islam.