Erbil, Iraq: The deaths of five nuclear scientists on Sunday in an ambush outside Damascus has raised anew suspicions that Israel is conducting an assassination campaign intended to blunt Iran's nuclear ambitions.

At least one of the men was an Iranian nuclear technician, according to Syrian state television, members of the internal security wing of Lebanon's Hezbollah militia and the Syrian Observatory for Human Rights, which monitors violence in that country.

Rami Abdulrahman, the observatory's director, described the dead as "five nuclear engineers" in a Facebook post, and said they worked at a scientific research centre"near the neighborhood of Barzeh, northern Damascus". The Britain-based observatory, which works with a network of informants in Syria, has a reputation for accurate reports on events there.

Syrian government officials later confirmed that at least one of the men was an Iranian "scientific consultant", but they released no details on the nationalities of the other four men killed.

Both Iran and North Korea have provided Syria with nuclear technical expertise in the past, most notably at a secret reactor facility that the Israeli air force destroyed in a surprise attack in northern Syria in 2007. That previously unknown facility was being built with the technical assistance of Iranian and North Korean scientists, according to statements made after the attack by American and Israeli intelligence officials. The facility, which US and Israeli officials said hid a Syrian attempt to start a secret nuclear weapons program, was rendered unusable in the strike and later was dismantled by the Syrians.