LONDON (AFP).- Queen Elizabeth II led Britain in paying silent tribute to the Commonwealth war dead on Remembrance Sunday, an annual event made particularly poignant this year on the centenary of the start of World War I.

The 88-year-old monarch, senior royals and politicians laid wreaths at the Cenotaph national war memorial in London, as thousands of military veterans looked on.

Security was tighter than normal amid heightened fears of the risk of a terror attack, but the programme of marches and military music was unaffected.

In Afghanistan, the queen's grandson Prince Harry returned to the country where he served two tours with the British army to lay a wreath at the NATO base at Kandahar.

The centrepiece of Sunday's events was the two minute's silence at 1100 GMT, observed by millions of people across Britain and marked in London by the firing of a 13-pounder World War I gun.

"Today we stand united to remember the courageous men and women who have served our country, defended our freedoms and kept us safe," Prime Minister David Cameron said ahead of the event.

"We remember all those who have fallen and those who have risked their lives to protect us."

He noted the "particularly poignant" timing of this year's events, 100 years after the start of World War I, 70 years after the D-Day landings and just as Britain was leaving Afghanistan.

Remembrance Sunday is the Sunday nearest to Armistice Day on November 11, the anniversary of the 1918 signing of the peace that ended fighting in World War I.

More than one million people from the British empire died in the four-year conflict, but the day has become a time to remember all the troops killed in wars since then.

It is thought there has been only one year -- 1968 -- without a British military fatality on active service since the end of World War II in 1945.

Security 'intensified 
Security this year was "intensified" following fears the event could be a target for attack, according to the head of Britain's armed forces, Chief of Defence Staff General Nicholas Houghton.

Police arrested four men overnight Thursday on suspicion of "Islamist-related terrorism", which media reports said concerned a plot intended for British soil.

"Certainly the proximity of the sense of threat for this weekend, which has intensified the nature of the security that's attendant on it, has contributed to quite a different feel about this year," Houghton told BBC television.

The national terror level was also raised in August to "severe", meaning an attack is "highly likely", due to fears over the threat of jihadists fighting in Iraq and Syria.

Scotland Yard said it had an "appropriate and proportionate" policing plan in place for the London commemorations.

The queen laid the first wreath followed by her husband Prince Philip, 93, her son and heir Prince Charles and grandson Prince William, all of whom have served in the military.

Forty-six high commissioners from Commonwealth countries then followed suit.

In a sign of the improved relations between Ireland and Britain, the Irish ambassador also laid a wreath for the first time in honour of thousands of Irishmen who died in British uniform.

New memorial for Iraq, Afghan wars 
Prince Harry, 30, met some of the troops he served with during his brief trip to Afghanistan, and also gave a reading.

More than 220,000 British troops fought in the recent wars in Iraq and Afghanistan, and 623 lost their lives.

Cameron on Sunday announced plans for a £1-million (1.3-million-euro, $1.6-million) national memorial to the troops in those conflicts, to be opened in 2016.

In the run-up to Remembrance Sunday, many Britons wear a paper red poppy symbolising the flowers which grew on French and Belgian battlefields during World War I.

This year, the moat of the Tower of London has also been filled with 888,246 ceramic poppies in art exhibit remembering every British military life lost in that conflict.


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