Palestinian police accused Egyptian security forces of killing four smugglers from the Gaza Strip and injuring three others on Wednesday by blowing up their cross-border tunnel.

Under pressure from Israel and the United States, Egypt has tried to stem the secret passages from its Sinai peninsula, which have allowed Palestinians in Gaza to import weapons and commercial goods in defiance of an Israeli-led blockade.

Detonating a bomb underground, Egyptian security forces collapsed a tunnel in which seven smugglers were working on Wednesday, a Palestinian police official said. Three died of smoke inhalation and a fourth from flying debris.

The other three tunnellers were admitted with injuries to a hospital in Rafah, a Palestinian town on the Egyptian border.

Egypt, now building an underground wall along the frontier, does not generally discuss its anti-tunnelling efforts.

Many Egyptians sympathise with the Palestinians and the Hamas Islamists who rule Gaza and refuse to forswear violence againt the Jewish state.