The 62-year-old, who won the European Cup three times with Liverpool, is receiving treatment in a hospital in Bournemouth, close to his home in Poole, Dorset.
No details of Souness’ condition were immediately available.
The Edinburgh-born former midfielder won 54 caps for Scotland during a playing career which also saw him win five league titles among his Liverpool honours and a Coppa Italia title with Sampdoria.
As a manager, he led Rangers to three Scottish titles and four League Cups, before winning the 1992 FA Cup with the Reds.
He went on to manage Turkish side Galatasaray - winning two domestic cup competitions - Blackburn, where he won the 2002 League Cup, Southampton, Benfica and Newcastle among others.
He features in the Scottish national team, Rangers and English football Halls of Fame and in a 2006 poll of Liverpool supporters was named as the ninth most popular player in the club’s history.
Since leaving the Magpies in 2006 he has worked as a media pundit for Sky Sports and Irish broadcaster RTE.
Our thoughts are with him.