Clinton says Afghanistan faces 'critical moment'

US Secretary of State Hillary Clinton said Wednesday that Afghanistan faced a critical moment on the eve of President Hamid Karzai's inauguration for a second five-year term.

Speaking after arriving in Kabul for the swearing-in ceremony, the top US diplomat said there was now a "clear window of opportunity" for Karzai to take action despite the controversy surrounding his re-election.

"We stand at a critical moment on the eve of the inauguration of President Karzai's second term," Clinton said, speaking to about 150 staff at the US embassy in central Kabul.

"There is now a clear window of opportunity for President Karzai and his government to make a compact with the people of Afghanistan.

"We want to be a strong partner with the government and the people of Afghanistan," she said.

Clinton arrived in Kabul amid tight security as one of around 800 guests at the swearing-in ceremony, which is set to take place at the presidential palace at 11:00 am (0630 GMT) Thursday.

She has been at the forefront of calls from Karzai's international backers for him to use his second term in office to eradicate endemic corruption in his government and deliver good governance to his people.

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 crack down on corruption after a controversial election mired in fraud.

Her visit, which was previously unannounced, was accompanied by rigorous security in the heavily-fortified capital, where suicide attacks have killed around 100 people in the last three months alone.