Twenty-one people have been killed and at least 100 others injured by three bomb explosions in southwest Baghdad, Iraqi officials say.

There was no immediate claim of responsibility for the blasts, but armed anti-government groups like al-Qaeda in Iraq generally tend to target Shia mosques and neighbourhoods.

Violence in Iraq has fallen dramatically since peaking in 2006 and 2007, but attacks have surged in recent months, especially against officials, government institutions and security forces.

Al Jazeera's Rawya Rageh reports from Baghdad