Vilanova has been battling cancer for over two years and was forced to step down as Barca boss last July.

Spanish National Radio reported that Vilanova was admitted to hospital last Friday and is in serious condition following the surgery to alleviate gastric problems.

Vilanova was Pep Guardiola's assistant during a glorious four-year spell for Barcelona between 2008 and 2012 during which the club won 14 trophies.

The 45-year-old replaced Guardiola at the start of the 2012/13 season, but was forced to take four months away from the job between December 2012 and April 2013 to undergo treatment in the United States after suffering a recurrence of the throat cancer which had been first diagnosed in November 2011.

Barca went onto win the Spanish La Liga title, equalling the record points tally, in his only season in charge before he resigned due to his ongoing health problems.