NEW YORK - The United States’ refusal to apologise for its November airstrike on Pakistani border posts killing 24 soldiers has led to the collapse of the latest round of negotiations between the two countries, The New York Times reported Saturday.

“The White House, angered by the recent spectacular Taliban attacks in Afghanistan, refuses to apologise,” the newspaper said in a dispatch from Islamabad. It said US special envoy to Afghanistan and Pakistan Marc Grossman left Islamabad Friday night with no agreement after two days of discussions with the top Pakistani leadership that were aimed at ending the diplomatic deadlock between the two countries.

The incident has damaged the precarious US-Pakistani partnership and provoked outrage in Islamabad, which has retaliated by cutting off NATO supply routes to Afghanistan. Both sides insist that they are now ready to make up and restore an uneasy alliance that at its best offers support for American efforts in Afghanistan as well as the battle against some extremist groups operating from Pakistan, the dispatch said. The administration had been seriously debating whether to say “I’m sorry” to the Pakistanis’ satisfaction — until April 15, when multiple, simultaneous attacks struck Kabul and other Afghan cities, it said. “What changed was the 15th of April,” an unnamed senior administration official was quoted as saying.

The US and Pakistan disagree about the precise sequence of events in the deadliest single cross-border attack of the 10-year war in Afghanistan, it was pointed out.  Pakistan denies shooting first, and has accused the Americans of an intentional attack on its troops. US military and intelligence officials claimed that the attacks were directed by the Haqqani network, a group working from a base in North Waziristan in Pakistan’s tribal belt, the report said.

 That swung the raging debate on whether Obama or another senior United States official should go beyond the expression of regret that the administration had already given, and apologise, the paper said.

Without the apology, Pakistani officials say they cannot reopen the NATO supply routes into Afghanistan that have been closed since November, the report said.

The US, in turn, is withholding from Pakistan between $1.18 billion and $3 billion of promised military aid. The continuing deadlock does not bode well for Pakistan’s attendance at a NATO meeting in Chicago in three weeks, assuming it is even invited, The Times said.

US administration officials acknowledged Friday that the stalemate would not be resolved quickly, the paper noted.