Krakow, Poland - US Defence Secretary Robert Gates said Friday he remained hopeful that a "reasonable" deal could yet be reached with Kyrgyz officials preventing the closure of the United States' only air base in Central Asia, which supplies US and NATO operations in Afghanistan.

"I continue to believe that this is not a closed issue and there remains the potential at least to reopen this issue with the Kyrgyzs and reach a new agreement," Gates said at a meeting of NATO defence ministers in Krakow, Poland.

"If we are not able to do that on reasonable terms, we are developing alternative methods of getting supplies and people into Afghanistan," Gates said.

His comments came within hours of Kyrgyz President Kurmanbek Bakiyev signing a decree giving the United States 180 days to clear out of the air base.

The move, which follows reports that Moscow offered Bishkek financial incentives to close the air base, had been overwhelmingly supported by the country's parliament on Thursday.

Russia, Tajikistan and Uzbekistan have meanwhile agreed to allow NATO to move supplies to Afghanistan through their territories. (dpa)