A suicide bomber killed one of the most powerful men in north Afghanistan on Saturday, underlining the spread of insurgent violence in once peaceful parts of the country and casting a shadow over plans for Afghans to take control of security.

A provincial police chief, at least two Afghan policemen and two German soldiers also died in the attack on political and military leaders, Afghan and Nato officials said.

They were meeting in the capital of northern Takhar province to discuss an operation against insurgents, and at least another 10 people were injured, including the provincial governor, said the governor's spokesman Faiz Mohammad Tawhidi.

Nato's commander for the northern region, German Major General Markus Kneip, was among the wounded but not seriously hurt, General Rainer Glatz told reporters in Berlin.

The most high-profile casualty was General Dawood Dawood, police chief of north Afghanistan, a former deputy interior minister and before that a close associate of mujahideen commander Ahmad Shah Masood.

The loss of such a prominent and influential leader is a big blow to a force which is struggling to professionalize and shake off a reputation for abuse and corruption as foreign forces prepare to hand over security responsibilities in coming years.

He had been energetic opponent of the growing insurgent movement in the north, fostering state-sponsored armed self-defense groups known as the Afghan Local Police and organizing campaigns against the Taliban.

The day of his death he held a news conference announcing the start of operation Hope, which aimed to oust the insurgents from Takhar and neighboring Kunduz, where they have only gained a strong foothold in recent years.

Takhar was once so peaceful that there is no major permanent base for foreign troops there. German troops supervise the area from a base in neighboring Kudzu province.

But violence has risen sharply in recent months, as the insurgency gathers strength in northern areas. The Taliban claimed responsibility for Saturday's attack, saying they were target ting top regional leaders.

A mosque bombing last October killed the governor of Kunduz while he was attending Friday prayers and a Dutch aid worker was taken hostage there the same month.

Earlier this week at least 14 people were killed in violent protests about a night raid by foreign forces.

Attackers in uniform

Dagwood's death may also complicate Nato efforts to prepare for the start of a security handover from foreign forces to Afghan soldiers and police in some parts of north Afghanistan.

Afghan President Humid Kara said he condemned the attack in the strongest terms.

"The martyrs of this brutal attack were those who tirelessly worked to bring peace in the country," he said in a statement.

The attacker was wearing police uniform, said Tahiti, making this the latest in a string of attacks by rogue members of the security forces or insurgents who have used uniforms to breach security cordons.

The police chief of Kandahar province, Khan Mohammad Khan was killed by another attacker wearing police uniform in mid-April, and authorities have struggled to find a replacement.

An insurgent in army uniform also struck inside the Defense Ministry headquarters in Kabul a few days afterwards, killing two although neither was a senior leader.

Fighters under pressure in traditional strongholds because of a surge in US troops are seeking spectacular urban attacks to underline their reach, and the use of rogue police and troops, or insurgents in uniforms, has been growing.

The Taliban this month announced the start of a long-expected "spring offensive," vowing to carry out attacks including suicide bombings on foreign and Afghan troops and government officials.-Reuters