近期欧洲频繁遭遇恐怖袭击威胁，出于安全方面的考虑，英国近日宣布禁止外国游客参观伦敦地标建筑大本钟，本国游客参观需向所属选区的国会议员提交书面申请。

Foreigners have been banned from visiting Big Ben over security fears.

Foreigners have been banned from visiting Big Ben over security fears.

Tourists from abroad were until recently allowed to tour the legendary¹ London landmark². But due to mounting（增加，爬上） security problems they have now been banned.

Clearance³ checks for foreigners which were to ensure that terrorists could not target the historic clock tower became too complex and costly⁴.

British citizens are still allowed to visit Big Ben, but must apply by writing to their MP.

Michael McCann, the Keeper of The Great Clock, said the policy had to change to maintain security at the iconic London monument.

He said: 'We used to get a lot of foreign tourists but you have to be a British citizen now. It just got too complicated with the security checks, as you can imagine.

'We don't do public tours but you can write to your MP with a reason for wanting to see it and they arrange a tour for you. We do a tour up to three times a day which sounds a lot but there are only 16 people on a tour.'

Before taking the 75-minute tour, guests have to pass through strict security checks at Portcullis House.

Under the supervision⁵ of armed police, each visitor passes through a metal detector⁶ and a wall-mounted camera takes a picture of their face before being issued with a photo security pass.

They are guided around the famous tower of Parliament, learning the history of the tower, the bell and how the most accurate public clock in the world works.

A spokesman for the House of Commons confirmed the ban on foreigners but said: 'The house does not comment in detail on security matters.'

He added: 'The process involves people approaching their MP and some kind of security checks take place, based on their residency in the UK.'

The UK Parliament website says: 'UK residents can arrange a tour through their local MP.

However, please be advised that space is extremely limited and early booking, 3-6 months in advanced, is strongly recommended. Overseas visitors cannot currently visit the tower.'