The start of competitive action at the London Olympics marks the end of an "exhilarating journey", according to organising committee chairman Lord Coe.

The 30th summer Olympiad will get under way this afternoon when Team GB face New Zealand at the Millennium Stadium in the group stages of the women's football tournament.

That will end a 2,576-day period of waiting for the British public since London won the right to host the Games on July 6, 2005.

Despite concerns over issues such as security and ticketing in recent weeks, Coe cut a relaxed figure as he visited Cardiff just a few hours before the Games' begin.

He said: "It seems barely credible that it was seven years ago that we snuck across the line in Singapore and started off on what has been an extraordinary journey.

"It's been a long journey and it's been just exhilarating, and now we are only few hours away from the start and it's fantastic."

The 55-year-old also paid a glowing tribute to those who have volunteered to help during the Games, as well as those providing security.

"I have been growing in confidence each day over the last seven years as I have seen the quality of people who have offered their services.

"I have met some of the volunteers here this morning, 70,000 of the best people you could possibly find, and when you look at the people who are going to stand watch over our safety, they are just extraordinary people.

"People ask me how I can sleep at night and why I am so relaxed, the honest answer is the quality of the people I know are out there working while I'm asleep.

"My responsibility over the next month of these extraordinary events is to make people feel good about themselves, as they should, because they are doing the best work of their lives and creating some history."

But Lord Coe again refused to reveal who will light the Olympic torch in Friday's opening ceremony.

Decathlete Daley Thompson and rower Sir Steve Redgrave are seen as two of the leading contenders.

But Coe said: "It's almost become the national pub game - who is going to light the flame at the ceremony?

"I can categorically tell you it won't be me.

"The great thing about this country and all the nations within it, we have got some of the most extraordinary current and past Olympians.

"When you think of Wales alone and what it has left Olympic sport you don't have to look much further than Lynn Davies and hopefully Dai Greene will be joining that elite band of men soon. But there's no shortage of choices."