The fatal attack on Jo Cox outside her constituency surgery has again raised questions about security around MPs as they conduct their work in Westminster and across the country.

When police searched murder suspect Thomas Mair's home following last Thursday's attack, they found "material relating to extreme right-wing and white supremacist organisations and individuals", the Crown Prosecution Service said.

The Community Security Trust said it had contacted several Jewish MPs since Mrs Cox's death "to offer support and advice should they require it, in addition to the help that all MPs get from the police".

Racist and apparently politically-motivated threats to politicians have been widely reported in the past five years, with a specific increase on the internet and social media.

A number of Jewish politicians have been targeted by far-right groups and others. Lee Scott, the former Conservative MP, was forced to organise police protection in his Essex constituency after receiving death threats during the 2010 general election campaign.

Luciana Berger, Britain's youngest Jewish MP, received thousands of antisemitic tweets in just a few days in 2014, which, according to friends, left her feeling isolated. The abuse was co-ordinated by a United States-based neo-Nazi group.

Ms Berger later said the "frustratingly slow" response from Twitter to the episode had made it more difficult for the police to stop the threats.

Three months ago, her fellow Jewish Liverpool MP Louise Ellman was targeted by activists "hell-bent" on attacking her at constituency party meetings - reportedly because she is Jewish.

The orchestrated campaign created an "intimidating and hostile" atmosphere for Jewish members, a Liverpool councillor said.

While security is tight around Parliament, with armed police guarding meeting rooms, offices and public areas in which MPs and politicians work, the situation is often more relaxed when they return to their constituencies.

Additional security measures were introduced by many politicians after Labour's Stephen Timms was stabbed while meeting constituents in 2010.