By Caroline Cheese BBC Sport Online at Wimbledon

Police at Wimbledon have moved to allay fears over security at the Championships amid public anxiety over a possible terror attack to coincide with American Independence Day.

Venus and Serena Williams are in action on Centre Court on 4 July, and a host of other American players are still involved in the tournament.

However, the Ground Commander for the Metropolitan Police at the Championships insisted security would be as tight as it has ever been.

"Security at Wimbledon is always of the highest priority and it is as tight this year as we feel is necessary," Chief Inspector Nick Woods told BBC Sport Online.

"There are no extra personnel on duty today but we have the option, as always, to draft in extra officers should the need arise.

"We have elaborate contingency plans should there be any incident which requires our attention."

As well as officers from the Metropolitan Police, Wimbledon employs over 400 Securicor guards and a similar number of stewards from the London Fire Brigade.

Officials at the All England Club admitted that though there would be deploying no extra staff on 4 July, those in attendance would be extra vigilant.

"We are fully aware of the occasion and what it means," said a spokesman for the Club.

"There will be heightened security in place and we will be aware of any information that is being put out."

Security at the Championships has been under scrutiny after two members of the public were able to bypass guards and get onto Centre Court.

And days later, a fan of Anna Kournikova walked unchallenged into the players' lounge to meet his idol.