CAIRO, April 23 (Reuters) - Egyptian President Mohamed Mursi's legal adviser resigned on Tuesday amid controversy over the ruling Muslim Brotherhood's attempts to force out thousands of judges, state television reported.

An official at the presidency said they were aware of the report of the resignation of Mohamed Fouad Gadalla but had no immediate official comment.

Opposition daily Al-Masry Al-Youm quoted Gadalla as saying that the army and the judiciary were among Egypt's cleanest institutions and should be reformed from within and not be subject to outside interference.

(Reporting by Shaimaa Fayed; Writing by Paul Taylor)