ISLAMABAD (Reuters) - Pakistan resumed flights at more airports but delayed until Tuesday the reopening of its airspace nationwide, aviation authorities said, as tension with India eased after a standoff that brought the nuclear-armed neighbors to the brink of war.

Pakistan shut its airspace last week, leaving thousands of travelers stranded and forcing carriers to reroute flights, but resumed partial operations at four airports on Friday.

Two more airports have since opened, the Civil Aviation Authority (CAA) said, adding that curbs were expected to be removed on Tuesday.

“Some airports are open,” its spokesman, Mustafa Baig, told Reuters on Monday, adding that airports in the capital of Islamabad, the southern port of Karachi, and the cities of Lahore, Peshawar, Quetta and Faisalabad were partly functional.

He did say not why the reopening of airspace, originally scheduled for Monday, had been delayed.

The partial resumption of flights follows a week of tension that appears to be easing after Pakistan released an Indian pilot shot down during an aerial clash over the disputed Kashmir region on Wednesday.

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

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

The twice-weekly Samjhauta Express train service linking the Indian capital of Delhi and the eastern Pakistani city of Lahore resumed on Sunday, after being suspended last week.