A bomb exploded outside a church in Egypt last night. The Egyptian health ministry says at least 21 people were killed and 43 injured. The interior ministry had earlier put the death toll at seven.

Initial reports blamed a car bomb, though officials are now suggesting it was a suicide bomber.

The blast occurred during a midnight New Year service at the church of St Mark and St Peter in the Sidi Bishr district of Alexandria. The video above shows the scene in the church at the moment of the explosion.

The BBC has a video of the aftermath and the Egyptian Chronicles blog has several others, along with some photographs. Some reports say that after the explosion Christians attacked a mosque nearby.

The authorities had previously announced a tightening of securityaround Egypt's churches in anticipation of possible New Year attacks.

Last year, seven people were shot dead outside a church in Upper Egypt following a midnight mass to mark the Coptic Christmas. In April, an Iraqi offshoot of al-Qaeda calling itself The Islamic State of Iraq threatened to attack Christians in Egypt.

Egyptian officials have accused "foreign elements" of carrying out last night's attack. This is a common response when untoward events happen but the style of the attack does suggest it could be the work of al-Qaeda elements rather than local militants.

Sectarian tensions are common in Egypt, though the government usually tries to deny their existence or to quieten them down without addressing the underlying issues. 

Posted by Brian Whitaker, 1 Jan 2011.