The British government has ordered a review of police safety measures to protect politicians following the fatal stabbing of Conservative Party MP David Amess.
Sir David, 69, was talking with voters at a church in the small town of Leigh-on-Sea east of London .
Police said they arrested a 25-year-old suspect and were investigating "a potential motivation linked to Islamist extremism".
Police have said the investigation is in the "very early stages", though multiple UK media outlets, citing sources, reported that the suspect was believed to be a British national with Somali heritage.
Britain's politicians were stunned by the highly public attack, which recalled the murder of a pro-EU lawmaker ahead of the Brexit referendum.
In June 2016, Labour MP Jo Cox was killed by a far-right extremist, prompting demands for action against what lawmakers said was "a rising tide" of public abuse and threats against elected representatives.
Ms Cox's sister Kim Leadbeater, who became an MP in the same constituency this year, said Sir David's death had left her "scared and frightened".
Tributes for David Amess are placed near the Belfairs Methodist Church in Eastwood Road North, in Leigh-on-Sea, Essex, England. Source: AAP
"This is the risk we are all taking and so many MPs will be scared by this," she added.
Home Secretary Priti Patel on Friday ordered police across the country to review security arrangements for all 650 MPs.
"We will carry on... We live in an open society, a democracy. We cannot be cowed by any individual," she told journalists after laying a wreath for her fellow Essex MP.
House of Commons Speaker Lindsay Hoyle promised no "knee-jerk reactions" but told Sky News: "We will take further measures if we need to".
Labour MP Chris Bryant wrote in The Guardian that "sensible measures" were needed both in parliament, which is typically heavily guarded, and in constituencies, where MPs often hold meetings in locations such as church halls and high-street offices.
"We don't want to live in fortresses. But I don't want to lose another colleague to a violent death," Mr Bryant added.
Increasing threats
MPs and their staff have been attacked before, although it is rare.
But their safety was thrown into sharp focus by Brexit, which stoked deep political divisions and has led to often angry, partisan rhetoric.
Ms Cox's killer repeatedly shouted "Britain first" before shooting and stabbing the 41-year-old MP outside her constituency meeting near Leeds, northern England.
A specialist police unit set up to investigate threats against MPs in the aftermath said 678 crimes against lawmakers were reported between 2016 and 2020.
Most (582) were for malicious communications, although other crimes included harassment (46), terrorism (nine), threats (seven), and common assault (three).
Separate figures indicated a sharp rise in reports since 2018, including three threats to kill.
Ex-MP Anna Soubry, who quit the Conservative party because of her opposition to Brexit, has spoken of being sent bullets during an intimidation campaign that also targeted her family.
An image of murdered British Conservative MP David Amess is displayed near the altar in St Peters Catholic Church at a vigil in Leigh-on-Sea, Essex. Source: AAP
"I do get frightened," she said at the time.
Sir David himself wrote about public harassment and online abuse in his book "Ayes & Ears: A Survivor's Guide to Westminster", published last year.
"These increasing attacks have rather spoilt the great British tradition of the people openly meeting their elected politicians," he said.
MPs have had to install security cameras and only meet constituents by appointment, he added.
MPs' staff have also spoken of bearing the brunt of abuse.
"I would get in and all I would do is go on Facebook and report death threats and delete them," said Jade Botterill, who worked for senior Labour MP Yvette Cooper from 2013 to 2019.
"I reckon I reported over 1,000 death threats," she said, adding it caused her sleepless nights and fears she would be attacked.
Brexit had been a turning point and staff working in constituency offices while an MP was in parliament were often on the frontline of daily public anger, she added.
