Bomber kills police chiefs and German troops

Nato's commander for the northern region and the governor of Takhar province were also in the provincial council gathering of political and military leaders, but survived the attack.

The most high-profile casualty was General Dawood Dawood, police chief of north Afghanistan, a former deputy interior minister and once 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 struggling to professionalise and shake off a reputation for abuse and corruption as foreign troops prepare to hand over security responsibilities in coming years.

It may also complicate Nato efforts to prepare for the start of a security handover to Afghan soldiers and police in some parts of north Afghanistan.

Takhar police chief Shah Jahan Noori, two other Afghan policemen and three German troops were also killed in the attack, said Faiz Mohammad Tawhidi, spokesman for the provincial governor. At least ten people were wounded.

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

The police chief of Kandahar province, Khan Mohammad Khan, was killed by another attacker wearing police uniform in mid-April. He has not yet been replaced.

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

The Taleban claimed responsibility for yesterday's attack, saying its fighters had targeted the meeting of senior leaders.

"Fighters are still inside the governor's compound," spokesman Zabihullah Mujahid said by telephone from an undisclosed location. The Taleban leadership often exaggerate claims about such attacks.

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

But violence has risen sharply in recent months, as the insurgency gathers strength in northern areas.

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

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 Afghan uniforms, has been growing.