ADVERTISING giant WPP has reported rising full-year sales and profits, helped by the collapse in the value of the pound, but warned of mixed prospects in the UK as Brexit negotiations get under way.

The company, headed up by Sir Martin Sorrell, said that revenue rose to £14.3 billion, up 18 per cent when taking into account weaker sterling.

Pre-tax profit rose 26.7 per cent to £1.9bn while like-for-like net sales increased 3.1 per cent.

Earnings generated overseas are given a boost when translated back into sterling, which has collapsed against the dollar and the euro since June 23.

Without the positive currency headwinds, revenue and profits would have risen 7.2 per cent and 12.5 per cent respectively.

But WPP added that "tepid" economic growth in 2017 could impact the business.

"Given continued tepid economic growth and recent weaker comparative net new business trends, the budgets for 2017, on a like-for-like basis, have been set conservatively at around two per cent for both revenue and net sales," WPP said.

Like-for-like net sales across the group were up just 1.2 per cent in January and the firm flagged Brexit as a concern.

"The prospects in the United Kingdom are more mixed as the post-Brexit vote scenarios will play out over the next two years and uncertainties about the possible outcomes increase," the firm said.