British MPs have been told to contact police to review their security following the killing of Jo Cox.
Tory chief whip Mark Harper and Labour counterpart Rosie Winterton are understood to have issued the advice after Mrs Cox, 41, was shot and stabbed in the street yesterday following a constituency clinic in West Yorkshire.
Meanwhile, a UK newspaper report has suggested that police had been reviewing the mother-of-two's security after she received threatening messages over a three-month period.
The Times says there is no known link between the reported messages and her killing.
A witness to yesterday's attack on Mrs Cox said the gunman "walked off very coolly, very slowly".
A 52-year-old man named locally as Tommy Mair was arrested a mile from the scene.
Conservative MP James Berry told Sky News: "The chief whip has given us very similar advice to the Labour chief whip. The main concern is around public events and surgeries.
"The tragedy here is that Jo was brutally murdered after her constituency surgery, trying to do her democratic duty. That's a big concern for all MPs who, like me, hold a weekly advice surgery."
The attack came a week after Tory whip Gavin Barwell was threatened outside his constituency office in Croydon.
And in the hours following Mrs Cox's death, a man was reportedly detained by police over an abusive phone call made to the office of MP Ben Bradshaw.
'Danger'
Bernard Jenkin, MP for Harwich and North Essex, said he no longer meets constituents alone.
"There have been times when I have suddenly felt I am in danger," he said. "I now conduct my surgeries with somebody else present."
A report for the UK's House of Commons Administration Committee last August revealed that security is a particular concern for women MPs.
Tributes to Mrs Cox have come in from all sides of the political divide and from foreign politicians including US presidential candidate Hillary Clinton.
The MP's husband Brendan released a statement saying "Jo believed in a better world and she fought for it every day of her life".
Vigils were held in Westminster and West Yorkshire yesterday evening.
