SILISTRA, Bulgaria — An annual Jewish pilgrimage to a rabbi’s grave site in Bulgaria went ahead Tuesday under heightened security in the wake of a July terror attack that killed five Israelis and one Bulgarian in the eastern European country.

The pilgrimage to the grave of Rabbi Eliezer Papo in the town of Silistra, on the Bulgaria-Romania frontier, drew some 500 worshipers, most of them from Israel.

Last year’s pilgrimage had nearly no visible Bulgarian security presence. This year, the road outside Papo’s gravesite was closed by police cars, buses had police escorts and lookouts were visible on rooftops as worshipers clustered for prayers around the grave. Armed officers, both uniformed and in plainclothes, stood nearby.

Israel’s ambassador to Bulgaria, Shaul Raz Kamisa, who was present at the event, praised Bulgarian authorities and called the security measures “unprecedented.”

“This is the result of their understanding that a new reality has been created,” he said.

Five Israelis and a Bulgarian driver were killed when a suicide bomber detonated himself at an airport near the Black Sea city of Burgas on July 18.

Israel has accused Iran of being behind the attack.

The pilgrimage to the grave of Papo, who died in 1828, is led every year by Yoshiyahu Pinto, an Israeli mystic rabbi who spends much of his time in the US and has followings in both countries.