No further flights will leave Belfast City or Intrnational airports today despite the possibility of restrictions on airspace being lifted.

Air traffic control company Nats said parts of Scottish and Northern Irish airspace would open from 7.00pm BSTon Tuesday evening to 1.00am BST on Wednesday.

Air passengers took advantage of a small window of opportunity today as five flights took off from Belfast for the first time in six days.

Northern Irish airspace reopened to allow aircraft to depart for Scottish destinations, with one inbound flight arriving from Edinburgh shortly before midday.

Officials said over 50 passengers left George Best Belfast City Airport after 10.15am bound for Glasgow and Aberdeen with FlyBe and the Isle of Man with Manx 2, after earlier uncertainty.

FlyBe flights to Inverness and Edinburgh were also expected to leave before midday. However, air traffic control body Nats said airspace would be closed again from 1pm until 7pm as a new volcanic ash cloud spreads towards the UK.

Nats said today: “The situation regarding the volcanic eruption in Iceland remains dynamic and the latest information from the Met Office shows that the situation today will continue to be variable.”

Operations director at City Airport, Mark Beattie, said the situation would be monitored continually throughout the day.

“The aircraft are all here and ready to go once they get the go-ahead from the authorities,” he said.

“We are waiting for operations to be allowed to resume and we are ready to react to what we expect to be a very fluid situation.”

Mr Beattie said if airspace restrictions were later relaxed, then BMI plans to operate one flight in and out of Heathrow, while Easyjet hopes to offer its passengers one flight in and out of Luton.

Northern Ireland’s airspace had been rescheduled to reopen at 7am, with plans to reinstate 20% of the services from the City Airport today. At the International Airport, all flights were cancelled, except those destined for the Isle of Man.

“We continue to advise customers to refer to their airline's website,” airport spokesman Uel Hoey said.

Among the passengers on the first flight from City Airport this morning was 13-year-old James McCourt, who goes to school in Glasgow.

“I was meant to go back on Sunday morning but it was cancelled,” James said.

His father Eugene, who was at the airport with him, added: “Every time he was delayed the smiles just got bigger.”

Melbourne woman Patricia Skinner said she was “delighted” to finally be getting away to Glasgow.

The volcanic eruption in Iceland has strengthened and the new cloud is spreading south and east towards the UK.

Elsewhere, hopes that the first flights would be taking off from City of Derry Airport this morning were dashed. The early morning Aer Arann flights to and from Dublin had to be abandoned at the last minute today amid fears over new eruptions of ash.

All other Ryanair routes have been cancelled until at least noon tomorrow.

An information officer at the airport confirmed that there would be no flights taking off from the airport today.

Flights later today will be limited to eastern Scotland and part of northern England as the volcanic ash cloud situation remains “dynamic”, Nats said.

It said that from 1pm to 7pm only part of Scottish airspace, including Aberdeen, Inverness and Edinburgh airports, would be available for flights in addition to airspace south to Newcastle airport. This will mean that there will be no flights after 1pm from Glasgow, which was among the airports that was able to open today and operate services.

Stressing passenger safety remained “paramount”, Prime Minister Gordon Brown said experts were looking at opening sections of airspace where it became available.

He also said the Government was putting in place arrangements to bring stranded British travellers home if they could reach ports on the other side of the Channel.

Transport minister Conor Murphy said the shutdown because of volcanic ash will not have been budgeted for by some operators.

“I am sure most airlines are operating on fairly tight budgets, the shutdown won't have been budgeted for in the financial plan of the airline,” he said.

“I would not be surprised if some of them are suffering financially as a consequence and it may well threaten the existence of some of them.”