The La Liga club cancelled a Christmas lunch with the media on Wednesday after reports that Vilanova's tumour has become malignant again.

The 44 year-old, who took over from Pep Guardiola earlier this year, endured emergency surgery in November 2011 on his parotid gland.

Vilanova guided Barca to their best-ever start in La Liga as they have gone unbeaten for 16 games, and sit atop of the table with 46 points, holding a 13-point lead over arch-rivals Real Madrid.

The news about Vilanova's health problems comes a day after defender Eric Abidal got the green light to make his comeback after spending most of 2012 on the sidelines after a liver transplant.

Barcelona have yet to comment on the matter, but are expected to release an official statement later on Wednesday.