IS group claims responsibility for Saudi Arabia's Shia mosque suicide bombing

At least 21 were killed, over 80 injured in the blast

The Saudi arm of Islamic State (IS) has claimed responsibility for the horrific attack on a Shia mosque in Saudi Arabia that took the lives of at least 21 people.

A suicide bomber struck Imam Ali mosque in al-Qadeeh, located in Saudi's Eastern Province, which was filled with worshipper for Friday prayers, the BBC reported.

The Saudi branch of IS, which formally came into being last November, claimed responsibility for the attack via a post on Twitter along with an image of the bomber.

According to Saudi health minister, at least 21 people had been killed and over 80 were injured in the blast, with some being wounded "very critically.".

A spokesman for the Saudi interior ministry said in a statement, "The security authorities will spare no effort in the pursuit of all those involved in this terrorist crime."

The Sunni extremists of IS were likely looking for an opportunity to worsen the situation between Saudi Arabia's Shia minority and the rest of the population.

A large Shia Muslim minority of the country is mainly based in the Eastern Province, and there have been protests by the community for greater rights.

The attack comes at the same time when the Saudis are leading a coalition of Arab states in an air campaign against Shia rebels in Yemen.