Deal struck to end US government shutdown - for three weeks - but does NOT include wall funds

“I have a very powerful alternative [an apparent reference to his belief that it is available to him to declare a national emergency], but I didn't want to use it at this time. Hopefully it will be unnecessary.”

It is understood the deal is to restore current government spending levels until February 15.

Mr Trump said border security must be part of any longer term deal, but the solution announced this evening does not include funding for the wall he wishes to build along the US' southern border.

"Barrier or walls will be an important part of the solution," he said.

Mr Trump's action to sign legislation to reopen government departments for three weeks would end what has become a record, 35-day partial shutdown.

Some 800,000 federal workers have had to work without pay or have been kept from doing their jobs as Mr Trump and congressional Democrats were locked in a stalemate over the billions of dollars that the president has demanded to build a US-Mexico border wall.

To those federal employees who have been without pay in recent weeks, he said: “In a short while I will sign a bill to reopen the government...I will make sure that all employees receive their backpay very quickly. Or as soon as possible. It’ll happen fast.”

He was speaking this evening as intensifying delays at some of the US' busiest airports and widespread disruptions brought new urgency to efforts to break the impasse.

Earlier: US reportedly close to short-term deal to end government shutdown

The White House and congressional leaders are reportedly near a short-term deal to end the longest government shutdown in US history.

It comes as US aviation officials reported delays in air travel because of a "slight increase in sick leave" at two East Coast air traffic control facilities.

Air traffic controllers and airport security agents have been working without pay since the federal shutdown began in December, and high absentee rates raise the possibility of long airport queues, or even worse.

White House spokeswoman Sarah Sanders said Donald Trump has been briefed on the delays and "we are monitoring the ongoing delays at some airports".

"We are in regular contact with officials at the Department of Transportation and the FAA (Federal Aviation Administration)," Ms Sanders said in a statement.

New York governor Andrew Cuomo wrote a letter to the president earlier today saying the shutdown is impacting safety and security at airports and putting travellers at risk.

FAA spokesman Gregory Martin said it had augmented staffing, rerouted traffic and increased spacing between planes as needed.

The staffing problems were at air traffic centres in Jacksonville, Florida, and a Washington DC site that controls high-altitude air traffic over seven states.

"The results have been minimal impacts to efficiency while maintaining consistent levels of safety in the national airspace system," Mr Martin said.

LaGuardia Airport in New York and Newark Liberty International Airport in New Jersey were both experiencing at least 90-minute delays in take-offs today.