Ryanair, the low-cost operator, is putting together costings for launching a new 12 flights-a -day operation from Belfast International Airport.

Industry sources say the no-frills operator has sought detailed bids from potential suppliers in the North and has indicated that it would be keen to establish services if it can negotiate a deal with TBI, the owner of Belfast International Airport.

A Ryanair spokeswoman said that Belfast International was one of a number of airports that it was currently talking to.

It is believed that Ryanair would be keen to launch a number of international services from Belfast - one of TBI's objectives is to increase the number of international flights it offers from Northern Ireland.

Ryanair's rival low-cost operator, EasyJet recently launched a direct Belfast to Amsterdam route, which has proved so popular that it increased the frequency of the service.

According to industry sources, it is likely that Ryanair would offer to provide a direct service to Paris and its new Continental hub at Charleroi near Brussels.

No deal has yet been agreed between Ryanair and TBI but discussions between the two parties could cast some doubts over the low-cost operator's current operations at the City of Derry airport.

Last year the airline carried more than 125,000 passengers from the City of Derry Airport to London Stansted This year it expects this to increase to 160,000 people.

Ryanair claims to carry on average around 10,000 passengers per month between Derry and London and, according to Mr Michael O'Leary, the airline's chief executive, it is the second fastest growing airport for Ryanair in Ireland.

However sources say Ryanair will not operate from two airports in the North and if it secures a deal with TBI at Belfast International, it is likely to relocate its Derry services to Belfast.