SHANGHAI: A blogger in China who made a death threat against Roger Federer said he had apologised, but remained at large after vowing to “assassinate” the world number one, according to an Internet posting.

An Internet user under the name “Blue Cat Polytheistic Religion Founder 07”threatened the Swiss top seed before he arrived to play at the Shanghai Masters, prompting organisers to step up security for the event.

“I have not been arrested,” said a posting on China's popular baidu.com site, where the original threat also appeared.

“I took the initiative to contact the relevant people to apologise,” said the message, which was posted around midday on Tuesday.

The original threat read: “On October 6, I plan to assassinate Federer for the purpose of tennis extermination.”

The user also posted a doctored image showing a decapitated Federer on his knees on a tennis court, with an axe-wielding executioner standing next to him.

Shanghai Masters organisers said last week ahead of the competition that they were taking the bizarre threat “seriously” while Federer himself labelled it a “distraction” after arriving in the Chinese commercial hub.

Federer's wife and twin daughters have not travelled to China but he said that decision had nothing to do with the threats.

He has been accompanied by security guards in dark suits who also stayed on the sidelines around the court when he practised on Tuesday.

Speaking after winning his opening match on Wednesday against Taiwan's Lu Yen-hsun, the Swiss 17-time Grand Slam champion said after one quick thought he had put the issue out of his mind.

“Once the match started, got under way, I never thought about it again,” he added.

Federer said he wanted to move on, adding: “It's not something I want to spend too much time thinking about to be honest because it shouldn't have been in the press in the first place. It's in the past now.”

A Shanghai police spokesman on Wednesday declined to comment on the case.

In 1993, former world number one Monica Seles was stabbed by a fan during a match in Hamburg.