Murder squad detectives have launched a probe after a man believed to be in his 40s was found stabbed to death on a London bus.

The man was found on the 189 bus in Gloucester Place, near Dorset Square, at around 12:10am BST.

The bus runs from Marble Arch Station in central London to Brent Cross Shopping Centre in the north west of the capital.

Police and paramedics rushed to treat the man, who has not been identified, but he was pronounced dead at the scene.

No arrests have been made yet and the man's next of kin have not been informed.

"Detectives are still at the location and enquiries are underway into the circumstances of when and where the stabbing took place," a Metropolitan Police spokesperson said.

"The Homicide and Major Crime Command has been informed. There have been no arrests at this stage and enquiries continue."

The street was cordoned off and a forensics tent was set up next to the double decker bus, the Evening Standard reported.