KABUL (AFP) — A suicide bomb exploded outside a mosque as worshippers were leaving after prayers in southwest Afghanistan on Thursday, killing 24 people, the provincial governor said.

Two senior police officers were among the dead and 34 people were also injured, some of them children, in the attack in Zaranj city, capital of Nimroz province bordering Iran, Ghulam Dastgir Azad said.

"There was a suicide bombing in front of the city's mosque and at this time we have 24 people confirmed dead and 34 wounded, some seriously," he said, adding that most of those killed were civilians.

It was not immediately clear who was behind the explosion -- which occurred next to a popular market outside the mosque -- but similar acts in the past have been blamed on Taliban militants.

The Taliban, who were in power between 1996 to 2001, are trying to topple the US-backed government of President Hamid Karzai and oust tens of thousands of foreign soldiers based here to fight them back.

Most of the deadly violence has occurred in the country's south and east -- a troubled region bordering Pakistan, where militants are active and are said to have some local support.

As part of their campaign, the Islamic rebels have frequently used roadside and suicide bombings against the heavily-armed NATO-led soldiers, but attacks have also targeted local police which back the government.

More than 70,000 foreign troops, the bulk of them operating under NATO's International Security Assistance Force (ISAF), are stationed in Afghanistan.

The Taliban last month announced it would launch a new offensive in the Afghan spring, as weather conditions improve in the mountainous country -- but ISAF dismissed the statement.

Nevertheless, the violence has increased.

Also on Thursday, Afghan and international forces killed 13 militants during operations in the south, while a top rebel commander was also captured.

Ten Taliban-linked rebels were killed in the province of Ghazni along a key highway linking the capital Kabul to southern Afghanistan, the interior ministry said in a statement.

It added "these terrorists were attacking passengers and supply convoys" and said two other rebels were wounded and some others captured.

Mahboobullah Sabawoon, the chief of Gilan district where the operation took place, confirmed the incident but put the death toll at nine.

The defence ministry meanwhile said in a separate statement that three Taliban fighters were killed in an operation elsewhere in Ghazni.

It gave no further details.

And the interior ministry, in another statement, said a prominent Taliban commander was captured in Taliban-infested southern Uruzgan province.

The rebel commander identified as Mullah Tor Jan was deputy governor of Helmand province during the Taliban's rule, provincial police chief Juma Gul Hemat said.

"The capturing of Mullah Tor Jan is a big achievement for the police," the ministry's statement said.