THERESA May has described an attack on a mosque in Egypt which left 235 people dead as "sickening".
The Prime Minister branded those who carried out the massacre "evil and cowardly".
Mrs May tweeted: "Appalled by the sickening attack on a mosque in North Sinai. Condolences with all those in #Egypt affected by this evil and cowardly act."
The atrocity took place at a Sufi mosque in Egypt's volatile Sinai Peninsula during Friday prayers.
Extremists attacked the al-Rawdah mosque in the town of Bir al-Abd, 25 miles from the North Sinai provincial capital of el-Arish, opening fire from four off-road vehicles on worshippers inside during the sermon.
READ MORE: Egypt mosque attack leaves hundreds dead
The attack, which has left more than 130 people injured, appears to be the latest by the area's Islamic State affiliate.
Police officers said victims were being transferred to local hospitals and militants had blocked escape routes from the area by blowing up cars and leaving the burning wrecks blocking the roads.
The attack was the largest single targeting of Egyptian civilians and the first on a large mosque congregation since the IS affiliate began its campaign of violence against the state following the military's 2013 overthrow of an elected but divisive Islamist president.
State news agency MENA reported that Egypt's presidency declared a three-day mourning period for the attack, as President Abdel-Fattah el-Sissi convened a high-level meeting of security officials.
READ MORE: Egypt mosque attack leaves hundreds dead
Cairo's international airport boosted security following the attack, with more troops seen patrolling passenger halls, conducting searches and manning checkpoints at airport approaches.
Security forces have been battling militants in northern Sinai for years, but attacks to date have focused on military and police assets, although assassinations of individuals IS considers government spies or religious heretics are not uncommon.
Hundreds of soldiers and militants have been killed in the conflict, although exact numbers are unclear as journalists and independent investigators are banned from the area.
READ MORE: Egypt mosque attack leaves hundreds dead
Egypt is also facing a growing number of attacks by militants in its Western Desert, including an attack last month that killed 16 police, according to an official tally issued by the Interior Ministry.
Security officials have told journalists that dozens more, including high-ranking counter-terrorism officers, perished in the October 20 attack some 84 miles south-west of the capital, Cairo.
Why are you making commenting on The Herald only available to subscribers?
It should have been a safe space for informed debate, somewhere for readers to discuss issues around the biggest stories of the day, but all too often the below the line comments on most websites have become bogged down by off-topic discussions and abuse.
heraldscotland.com is tackling this problem by allowing only subscribers to comment.
We are doing this to improve the experience for our loyal readers and we believe it will reduce the ability of trolls and troublemakers, who occasionally find their way onto our site, to abuse our journalists and readers. We also hope it will help the comments section fulfil its promise as a part of Scotland's conversation with itself.
We are lucky at The Herald. We are read by an informed, educated readership who can add their knowledge and insights to our stories.
That is invaluable.
We are making the subscriber-only change to support our valued readers, who tell us they don't want the site cluttered up with irrelevant comments, untruths and abuse.
In the past, the journalist’s job was to collect and distribute information to the audience. Technology means that readers can shape a discussion. We look forward to hearing from you on heraldscotland.com
Comments & Moderation
Readers’ comments: You are personally liable for the content of any comments you upload to this website, so please act responsibly. We do not pre-moderate or monitor readers’ comments appearing on our websites, but we do post-moderate in response to complaints we receive or otherwise when a potential problem comes to our attention. You can make a complaint by using the ‘report this post’ link . We may then apply our discretion under the user terms to amend or delete comments.
Post moderation is undertaken full-time 9am-6pm on weekdays, and on a part-time basis outwith those hours.
Read the rules here