Lawrie Sanchez is the new full-time manager of Fulham

Sanchez took over temporarily at the English Premiership club in April and helped them avoid relegation.

He said: "I've always wanted to manage at the highest level and Fulham have given me that opportunity."

"Northern Ireland will be a great job for someone and I leave the team in good shape with them at the top of their Euro 2008 qualifying group."

He added: "I wish them all the best for the future. They're disappointed but I hope they understand my actions."

In a statement, the IFA said: "We would be the first to congratulate him on his appointment as their new manager and to recognise the outstanding job he has done for Northern Ireland football and the IFA.

"The IFA will be considering its position over the next few days and no further comment or statements will be made."

'Rolling contract'

A spokesman for Fulham said Sanchez had been appointed permanent boss on an "indefinite, rolling contract".

Sanchez leaves Northern Ireland top of their Euro 2008 qualifying group.

They have six key games between August and November which will decide whether they qualify for the finals in Austria and Switzerland next summer.

Sanchez temporarily took charge of Fulham in April and steered them to Premiership safety after the sacking of Chris Coleman.

At the time, Sanchez insisted he believed he could combine his international and domestic duties.

"I think it is possible to do both, and I have read one or two people say it's impossible," he said.

"As an international manager, I know I can do the international job and a top job at the same time."