United Nations, Sep 30 (IANS) UN Secretary-General Ban Ki-moon Monday congratulated Ashraf Ghani Ahmadzai on his inauguration as the new Afghan president and called for a new Afghanistan government's formation at the earliest.

Ghani was sworn in Monday, marking the first ever peaceful power transition in the history of the conflict-ridden country.

"The secretary-general notes the serious challenges facing Afghanistan and calls for the new government to be formed quickly and to work with all Afghans in a spirit of national unity," Xinhua quoted a spokesperson of the UN chief as saying in a statement.

"He applauds the great determination, patience and strength demonstrated by the Afghan people, and encourages the new government to uphold these virtues as it moves the country forward."

Ban also extended his greetings to Abdullah Abdullah on being sworn in as chief executive officer of the new Afghan government.

The inauguration follows a political deadlock over a vote in which both Ghani and rival Abdullah claimed victory. A UN-supervised, Afghan Independent Election Commission-run audit followed with more than 22,000 ballot boxes reviewed.

As soon as Ghani took the oath of office, he issued a decree appointing Abdullah the chief executive of his government. They are expected to begin the difficult process of agreeing on cabinet ministers and other positions soon, according to an agreement they signed on forming the national unity government.

Afghan Foreign Minister Zarar Ahmad Osmani, addressing the annual debate of the UN General Assembly in New York Saturday, said Afghanistan had achieved a "significant milestone" with the conclusion of the presidential election.

He said the country was "on the eve of a transformative decade" with the transfer of security responsibilities from an international coalition force to the Afghan community by the end of this year.