Flinders Street Station cleared of threat

A man looking at pictures of dead bodies on his phone sparked a 'lock down' on two platforms at Melbourne's Flinders Street Station.

The central railway hub was deemed safe after police spoke to a man at the station following complaints on Thursday morning.

Victoria's Chief Commissioner Graham Ashton said people are on heightened alert after a terrorist attack killed five people in London overnight.

"People are being extra alert, which is what you want," Mr Ashton told 3AW.

"We just had a report that somebody was looking at deceased bodies on a mobile phone," he said.

"It turned out that there was nothing in it".

Fairfax media had earlier reported the station was "hectic", with police cars mounting the pavement and passengers claiming they were stuck on trains trying to get into the station.