ISLAMABAD (Reuters) - Pakistan will push back the deadline for companies to express interest in buying national carrier Pakistan International Airlines to May 18, the country's privatisation minister said on Thursday.

The extension, announced in a statement by Minister for Investment and Privatisation Abdul Aleem Khan, came a day before the expressions of interest had originally been due. He said 10 companies had already expressed an interest.

"The Board accorded approval for extension in the date for submission of interests on the request of interested parties," he said, referring to the Privatisation Commission Board he leads.

Pakistan's government has previously said it is putting on the block a stake of between 51% and 100% in the loss making airline as part of reforms urged by the International Monetary Fund.

The disposal of the flag carrier is a step past elected governments have steered away from as it is likely to be highly unpopular, but progress on the privatisation will help cash-strapped Pakistan pursue further funding talks with the IMF.

(Reporting by Charlotte Greenfield in Islamabad and Ariba Shahid in Karachi; Editing by Kirsten Donovan)