ISLAMABAD (Reuters) - Four Pakistani airports were beginning partial operations on Friday and they will fully resume commercial flights on Monday, the Civil Aviation Authority said, after airports were closed when military tensions with India erupted earlier this week.

Karachi, Islamabad, Peshawar and Quetta airports were resuming some flights on Friday, with the remainder opening next week, a spokeswoman said.

Airspace for all commercial flights would be re-opened on Monday at 1:00 p.m. (0800 GMT), she said.

The re-opening of Pakistani airspace came amid signs the conflict between the two nuclear-armed neighbors was cooling. On Friday, Pakistan handed back to India a pilot who was captured after his MiG-21 jet was shot down by a Pakistani fighter during an aerial clash over the disputed Kashmir region on Wednesday.

The airspace closure disrupted not just Pakistan’s air transport but flights worldwide as airlines were forced to cancel or reroute flights to other destinations that pass over Pakistan.

Flights between Asia and Europe were severely affected, with thousands of passengers stranded, although airlines were later able to reroute many flights through China that normally pass over Pakistan.

Flights from Singapore to Europe that usually cross Pakistan and Afghanistan, for example, were re-routed westwards over Oman, adding over an hour’s flying time and higher fuel costs. Iran also saw heavier use of its airspace, officials said.

Pan-European air traffic agency Eurocontrol said a total of 400 flights had been affected, with especially severe impact on Georgia and Azerbaijan and some effect on Poland.