Three bombings in Baghdad, including a car bomb in a market, killed five people Thursday, the latest in a surge in Iraq violence that has sparked fears of a revival of all-out sectarian war.

Twin roadside bombs in southwest Baghdad killed three people, while a car bomb in a market in the capital's southeast killed two others, security and medical officials said.

Attacks in Baghdad and elsewhere have risen sharply, with May Iraq's deadliest month since 2008, as persistent political disputes have given fuel and room for militants to increase their activities.

There has been a heightened level of violence since the beginning of the year, coinciding with rising discontent in the Sunni Arab minority that erupted into protests in late December.

Authorities have failed to bring the wave of unrest under control, and have not addressed the underlying political issues that analysts say are driving the attacks.

The UN envoy to Iraq has warned that the violence is "ready to explode".