More than 4,000 doping tests will be carried out during the 2008 Beijing Olympics, a 25 percent increase over the number of controls at the 2004 Athens Games.

International Olympic Committee medical director Patrick Schamasch said Tuesday that up to 4,600 urine and blood checks will be made from the period of the opening of the athletes' village until the end of the games.

The biggest increase will be in the number of pre-competition tests, he said.

The total is nearly double the 2,000 tests conducted at the 2000 Sydney Games and is an example of the IOC's "zero tolerance" policy on performance-enhancing drugs, spokeswoman Giselle Davies said.