Hamas blamed Egypt on Monday for the deaths of eight Palestinians, claiming it used water, gas and explosives to seal a network of tunnels under its border with the Gaza Strip.

Hamas Interior Ministry spokesman Ehab al-Ghsain criticized Egypt's anti-smuggling tactics as dangerous. Three Palestinians were crushed to death on Monday when their tunnel under the border collapsed, medics said. Five others suffocated on Aug 1.

Smugglers have dug dozens of tunnels to move people and contraband, including arms and ammunition, between Egypt and the Gaza Strip. Egypt and Israel have restricted the flow of goods into the coastal territory after Hamas took control of it in June 2007.

Egyptian security sources confirmed that Egypt had pumped gas into tunnels in recent months before sealing them off.

They said the gas was not harmful and was used to prevent Palestinians from trying to re-enter the tunnels.

The sources said Egyptian authorities typically informed their Palestinian counterparts once the tunnels were sealed.

Egypt's Interior Ministry had no immediate comment.

Hamas blew up the Rafah border crossing in January, allowing hundreds of thousands of Gazans to pour into Egypt to stock up on supplies. Egypt resealed the border and has stepped up patrols to prevent another breach.

The United States and Israel have pressed Egypt to seal the tunnels to stop militants from smuggling weapons. U.S. experts have been helping Egyptian security forces look for tunnels.

"We understand the American and Israeli pressure on Egypt but that does not justify the killing of people in such a manner," Ghsain said.

He defended Gaza's tunnel network, saying it was a result of the blockade.

"Once the Rafah crossing opens and the blockade is lifted, the tunnel issue will be resolved," he said.