WASHINGTON - The top UN official in Afghanistan called Tuesday on its President Hamid Karzai to show his commitment to reform in his next cabinet, bluntly warning that the world could desert him otherwise.

Karzai has pledged to fight corruption in his new term after an election tainted by fraud allegations, which has led to growing tension between him and US President Barack Obama's administration.

"We are really at a turning point," Kai Eide, the UN special representative to Afghanistan, told US public broadcaster PBS in an interview in Kabul.

"I think the debate we've seen over the last few months in the international community will become even more heated, even more difficult, if we do not have an important, positive signal given through the composition of a new government," he said.

"Some Afghans believe that Afghanistan is of such strategic importance that we will stay here whatever happens. It is simply not correct," he said.

The Obama administration, which is considering boosting the number of troops in Afghanistan, has criticized Karzai's alliance with warlords accused of human rights violations and drug trafficking.

Karzai appeared at his news conference Tuesday alongside one such controversial figure, his vice presidential pick Mohammad Qasim Fahim.

Eide's blunt remarks come after criticism that the Norwegian was too hesitant in pressuring Afghan authorities to eliminate voting fraud. The United Nations sacked his American deputy, Peter Galbraith, after he raised concerns about ballot-stuffing.