Police are investigating a death threat against Liverpool manager Gerard Houllier.

The club confirmed that the threat is now the subject of a Merseyside Police probe.

It is understood that the content of the letter, written on a single piece of A4 paper, claimed to know precise details of the manager’s daily routine as well as the layout of his apartment in the city.

After the recent FA Cup defeat at Portsmouth, graffiti was daubed on the wall at the club’s training ground, with one message reading: “Hope you die of Aids, Houllier.”

A Liverpool spokesman said: “It was worrying enough to involve the police. They are still investigating.”

The spokesman added: “It was very unpleasant and because of that we have involved the police in the situation.

“We do not want to over-dramatise the incident, but such letters cannot be ignored.”

Houllier has been under pressure for weeks following a disappointing season, but the Liverpool manager has vowed to fight on.