The world's biggest advertising group WPP has reported better than expected first-quarter net sales.

The company also reiterated its full-year guidance in the first set of results to be published without founder Martin Sorrell. 

The UK group said its like-for-like net sales were down 0.1% compared with analyst expectations of a drop of around 1% due to lower spending from clients such as Unilever and P&G and as tech groups Google and Facebook encroach on its turf. 

WPP is looking for a new chief executive after Sorrell stepped down over two weeks ago due to an investigation into personal misconduct. 

His departure has sparked speculation that a new leader could sell off assets or restructure the group after it struggled to match the better performances of its peers Omnicom, Publicis and IPG. 

Joint chief operating officers Mark Read and Andrew Scott are running the company in Sorrell's absence.

They said they would review the British group's strategy, focus on growth and address the parts of the business that are struggling. 

"We are pleased to announce the group's first quarter trading update, which is in line with our expectations," WPP's executive chairman Roberto Quarta said. 

"Our guidance for 2018 remains unchanged," he added.