POLICE have confirmed they arrested a Chelsea fan for throwing a smoke grenade on the pitch at St Mary's.

It was one of four explosions let off inside the stadium during Saturday’s FA Cup clash, while a flare was found discarded outside.

Police last night confirmed they had arrested an away fan for throwing the smoke grenade, although it is understood he had picked it up and not ignited it himself.

They revealed the issue of fans carrying pyrotechincs is part of a wider problem being experience at football grounds nationwide.

Supt Rick Burrows, in charge of football policing for Hampshire, said supporters carrying smaller sized flares similar to those used in paintballing were becoming more commonplace and could not be easily detected.

He told The Daily Echo; “Four flares were set off during Saturday’s game, all of them in the away supporters area.

“One of those was thrown onto the pitch and was dealt with by safety stewards who extinguished it.

“We are seeing a large increase nationally and the pyrotechnics we are talking about are very small and therefore can be easily hidden.

“Short of intrusive searching of everyone entering a football stadium we have to rely on the fans themselves to self-police and help us with that.

“We need the support of the crowd to help deter others from doing that.”