(Updates toll)

KABUL, April 1 (Reuters) - Nine people, five of them children, were killed in a suicide bomb attack on an army convoy in Afghanistan on Sunday, police said, while the Taliban hanged three men after accusing them of spying for British troops.

With the approach of spring, violence has surged in Afghanistan in recent weeks, following the bloodiest period last year since the Taliban's ousting from power in 2001.

The suicide bomber rammed a car into an army convoy in Mehtarlam, the provincial capital of eastern Laghman province, and killed two soldiers, police said. The children along with two other civilians were near the attack.

"It was a suicide attack and several civilians were also wounded apart from civilian deaths," Yar Mohammad, a senior provincial police official, told Reuters.

At least a dozen people, including the troops were wounded in the attack, witnesses said.

There was no immediate claim of responsibility for the attack, but Taliban guerrillas have unleashed a series of suicide raids and other attacks against Western and Afghan troops in the past.

Earlier on Sunday, the Taliban hanged three men from trees in front of residents in the town of Musa Qala in southern Helmand province after accusing them of being spies for NATO's British troops.

Helmand is part of the Taliban's stronghold and the main drug producing region of Afghanistan, the world's leading producer of heroin.

"They were spying for the British troops and had tipped them off about the location of one of our commanders who was killed by an air strike," Nizamuddin, a provincial Taliban commander, told Reuters by telephone from the district.

The Taliban have returned to dominance in Musa Qala and surrounding areas since the collapse of a truce brokered by tribal elders last year between militants and British troops.

The area has been the scene of a series of clashes between the Taliban and Western forces this year.

In neighbouring Kandahar province, Taliban guerrillas killed seven policemen in an ambush on Saturday, provincial police said.

Violence is increasing ahead of an expected spring offensive by the Islamist militants. Nearly 4,000 people, about a quarter of them civilians, died last year in violence between the Taliban and Western troops.

About half the dead were Taliban guerrillas, Western and Afghan military commanders have said.

A blast in Kabul during the day sparked fear among residents, but officials said the army had blown up seized explosives and mines in a controlled explosion. Kabul has been hit by several bombs in recent months.

This year is seen as a crucial one for both the Taliban and the Western forces led by NATO and the U.S. military.

The Taliban have vowed to drive out Western troops and topple the government of President Hamid Karzai.

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