Sebastian Coe says London will not be turned into a "city under siege" by the heavy security measures put in place for the Olympics.

About 75,000 spectators are expected at the Olympic Park on Saturday for five test events ahead of the July 27-Aug. 12 games.

It comes as the British military embarks on a series of operations to test Olympic security, including flights over London by fighter jets and helicopters.

Coe, who heads the local organizing committee, says "we want to make sure these games are safe and secure but at the same time we are not presenting a vision of London that is a city under siege."

Visitors to the Olympic Park encountered lengthy delays at times Wednesday as they went through airport-style security checks.

Coe says "there will be some queuing. This is an Olympic Games."