Clinton arrives for Karzai inauguration

US Secretary of State Hillary Clinton flew into Kabul on Wednesday to attend the inauguration of Afghan President Hamid Karzai for another five years in power as tight security brought the city to a halt.

The visit is Clinton's first to Afghanistan as Washington's top diplomat, underscoring the huge US pressure on Karzai to commit to serious reforms and crackdown on corruption after a controversial election mired in fraud.

Her arrival, which was previously unannounced, was accompanied by rigorous security underscoring increasing instability in Kabul where suicide attacks have killed around 100 people in the last three months alone.

State Department spokesman Ian Kelly confirmed Clinton would attend Karzai's inauguration, "meet with Afghanistan's leadership, international partners and allies, US troops, staff in provincial reconstruction teams, and embassy staff".

Clinton has been at the forefront of international pressure on Karzai to ensure his next government is clean, directly linking future levels of military and financial aid to progress in eradicating endemic official corruption.

Few on a guest list of 800 were expected to rank above foreign minister for the event scheduled for 11:00 am (0630 GMT) Thursday at the heavily guarded presidential palace in central Kabul, Western diplomats said.

"By not attending, (Western heads of state) are sending the message that I am not your friend any more," one diplomat told AFP on condition of anonymity.

"Karzai has to earn political capital because he has none left," he said.

"The key variable is the ministers," he said, referring to the cabinet that Karzai is expected to announce in about two weeks and which should reflect how he intends to respond to international pressure to reform his government.

To many Afghans, Karzai's presidency lacks legitimacy, his government lacks authority, and the way in which he took the presidency lacks credibility.

He was declared re-elected on November 2, by his own officials after massive ballot-stuffing -- mostly in Karzai's favour -- marred the August 20 election and his challenger Abdullah Abdullah withdrew from a run-off.

Karzai has come under intense pressure to ensure his next government is clean, as the astonishing levels of official fraud revealed by the election have seen Western public opinion turn against support for Afghanistan.

US President Barack Obama said Wednesday that his decision on whether to send more troops to Afghanistan would be announced "soon".

Diplomats said Washington expects Karzai to use his second term to take the helm of the war as an active and involved commander-in-chief.

"The US is keen to have Karzai show himself on the ground, to show that he not only endorses but is at the forefront of the military effort," a European diplomat said.

The British are hoping to hear pledges that his next government will be "competent, committed and clean," he said, according to conditions laid down by Prime Minister Gordon Brown for continued financial and military support.

The United States and NATO members have more than 100,000 troops in the country fighting to end a Taliban-led insurgency that threatens the Kabul government and is increasing in intensity.

The capital is on high alert for Taliban attacks to coincide with Karzai's inauguration, with many foreign employees of embassies, the United Nations and aid groups ordered to remain indoors, at home.

Kabul's international airport and major roads leading to the city centre were closed to civilian traffic with Afghan and international security forces on stand-by in case of Taliban attacks.

"The ceremony will be attended by 800 people, about 300 of them foreigners, including ambassadors, diplomats and high-ranking foreign guests," presidential spokesman Siamak Herawi told AFP.

Armed police and paramilitary units patrolled Kabul roads and intersections, and combined security forces -- army, police and intelligence -- threw a ring of steel around the city, a security official said.

Convoys bringing international VIPs -- foreign ministers and special representatives to Afghanistan -- sped through the city streets flanked front and back by pick-up trucks packed with heavily-armed guards and police.

The red, green and black Afghan flag fluttered from lamp posts as the presidential palace declared Karzai's inauguration a "glorious" moment.

Thursday has been declared a public holiday for Kabul and residents have been asked to avoid unnecessary movement.