JALALABAD - A Taliban suicide bomber on a motorcycle killed at least 12 army recruits on a bus in eastern Afghanistan on Monday, officials said, hours after a similar attack killed two people in the capital Kabul.

The latest blast hit a bus in the Sorkh Rud district of Nangarhar province, which borders Pakistan. Twelve bodies and at least 38 wounded had been taken to the main hospital in Jalalabad, the principal city in eastern Afghanistan, hospital chief Ihsanullah Shinwari told Reuters.

The number of casualties was expected to rise, several officials said.

"The suicide bomber was on a three-wheel motorcycle and targeted new army recruits who were heading to Kabul for training," said a police official, who asked not to be identified because he was not authorised to discuss matters concerning the Afghan army.

Defence Ministry spokesman Dawlat Waziri confirmed one of the ministry's buses carrying army recruits had been attacked but put the number of wounded at 26. "It was a crowded area and it is hard to say now how many of them were from the defence ministry," Waziri said.

Hours earlier, a bomb hit a mini-bus carrying Education Ministry workers in eastern Kabul, killing two people and wounding seven, the ministry said. Taliban spokesman Zabihullah Mujahid said the Islamist group had carried out the attack outside Jalalabad. However, no group had claimed responsibility for the Kabul attack.

Government workers and members of the security forces are often targeted by insurgent groups, including the Taliban, who are seeking to topple the U.S.-backed government in Kabul. The Taliban have stepped up their insurgency since most foreign troops withdrew from Afghanistan at the end of 2014, although Kabul had enjoyed a period of relative calm during the harsh winter months.

That lull was expected to end soon with the Taliban poised to launch their annual spring offensive. In Kabul, bus conductor Rahim Gul said the force of the blast threw him out of the vehicle.

"We picked up the Education Ministry staff and we were driving on the road when there was an explosion," Gul told Reuters Television. "It was very powerful and threw me out of the car window. A few minutes later I found myself in a wheat field and then I rushed to the site of the attack and helped some injured people and they were taken to hospital."

AFP adds: Taliban spokesman Zabihullah Mujahid later claimed responsiblity on his verified Twitter account. The group have been waging a revolt against the government since being toppled from power in 2001, frequently targeting the military.

They have stepped up their campaign following the 2014 withdrawal of US-led combat troops, winning a number of important military victories including the brief capture of northern Kunduz city last September. Afghanistan, the US, China and Pakistan in January formed a four-way group to try to jump-start peace talks that were first held in Islamabad last July but fell away after it emerged later that month the Taliban's founder Mullah Omar was dead, leading to infighting within the group.

But the Taliban have refused to return to the negotiating table until their conditions are met, including the departure of 13,000 foreign soldiers who are on a mission to train and advise their Afghan counterparts. Omar's successor Mullah Akhtar Mansour meanwhile is seen as rapidly consolidating his authority over dissident factions and has announced he is preparing for "decisive strikes" this spring.

The Syria-headquartered Islamic State group has also gained a foothold in Nangarhar province in recent years. Brigadier General Wilson Shoffner, a spokesman for the US-led military operations in Afghanistan, said in March the group was mainly contained in one district of the province. Many of them are former Pakistani Taliban fighters who "have changed allegiance to Daesh," Shoffner said, referring to the group by its Arabic acronym.