Pakistan has told U.S. special envoy Marc Grossman that it is "not possible at the moment" for him to visit the country, a senior government official told Reuters on Wednesday.

He did not elaborate on the reasons.

Marc Grossman is consulting US allies in the greater Middle East region on a move to involve the Taliban in the Afghan reconciliation process.

“We received word that the Pakistani government felt that it would be best to wait until this parliamentary review is concluded,” State Department spokesman Mark Toner told a briefing in Washington.

Mr Toner, however, emphasised that Pakistan continued to have “a central role” in the Afghan reconciliation process despite the challenges the two sides had faced in the past months.

“I don’t think it has changed,” said Mr Toner when asked if the US position on Pakistan having a central role in the process had changed.

Relations between Islamabad and Washington plunged to the lowest point in years when a NATO cross-border air attack killed 24 Pakistani soldiers on November 26.