CAIRO — The Egyptian government has begun sealing a series of smugglers' tunnels between its border and the Gaza Strip, witnesses and security officials said Sunday, in an apparent attempt to increase security after a violent cross-border incident with Israel set off the worst diplomatic conflict between the countries since the Camp David Accords.

The area around the town of Rafah is rife with smuggling, as hundreds of tunnels ferry construction materials, consumer goods and weapons into Gaza to bypass the Israeli blockade. Israel contends the tunnels also facilitate attacks by extremists.

The smuggling has only increased since the ouster of former Egyptian president Hosni Mubarak in February, as police officers pulled back from the Sinai Peninsula in the early days of the uprising, decreasing security in the area.

On Aug. 18, extremists, who Israel said had crisscrossed from Gaza into Egypt and back again, attacked an Israeli resort town, killing eight. Israeli security forces killed five Egyptian border guards in the crossfire as they pursued the attackers. Since then, a new resolve to secure the region has set in on both sides of the border.

The Egyptian military "brought their stones and their concrete," using large equipment to destroy the tunnels, in some cases filling them with concrete and gravel, said Fathy al-Nahas, 40, a contractor who owns a small tunnel near the border with Gaza, in a telephone interview Sunday. He said he used his tunnel, which he said was too narrow for a person to fit into, to send building supplies into Gaza.

The action was a sign that Egypt remained too close to Israel, he said, adding, "The government won't upset Israel or America."

Thousands of Egyptian troops have fanned into Sinai in the last month as Egypt has attempted to increase security. The heightened troop presence is yet another sign of the new relationship taking shape between Israel and Egypt, after decades in which Mubarak's tolerant if unenthusiastic stance toward Israel was far more conciliatory than Egyptian public opinion.

The Camp David Accords, the historic peace agreement between Egypt and Israel signed in 1978, limit the number of Egyptian troops that can be stationed in Sinai. In May, Egypt reopened the Rafah border crossing into Gaza, after closing it in cooperation with Israel when Hamas took over the administration of Gaza in 2007.

Also

Prime Minister Benjamin Netanyahu on Sunday emphatically ruled out an apology for a deadly raid on a Turkish ship leading an aid flotilla to Gaza last year. Turkey announced Friday that it was expelling Israel's ambassador after the leak of a United Nations report on the May 2010 incident found that Israel's naval blockade of the Gaza Strip was legal but that its troops used excessive force in the raid, in which nine Turks were killed. Along with an apology, Turkey has demanded compensation for the families of the dead and the lifting of Israel's naval blockade of Gaza, which Israel says is intended to prevent arms smuggling to the territory, run by the militant Islamist group Hamas.