AMMAN, Jordan - A day after a senior U.S. diplomat was assassinated, Jordan began rounding up dozens of men with links to training camps in Afghanistan or other militant Islamic causes, seeking clues to who might have been behind the attack, security officials and Western diplomats said yesterday.

In addition, security around diplomatic residences was significantly beefed up, with units deployed near previously unguarded foreign institutions such as cultural centers and schools, as the government sought to buttress the sense that Jordan remains a country where Westerners can feel safe.

Newspaper editorials and columnists inveighed against the killing of the diplomat, Laurence Foley, but only in private did officials characterize the act as terrorism. Publicly they maintained that there was not enough evidence to make such an assertion.

A Western diplomat said a man was seen leaving the area of the attack in a car driven by someone else - an indication that the likely gunman did not act alone.

"Otherwise," noted another Western diplomat, "there is no one fact, no evidence that gives us any clue the way the operation took place."

He also said the killing, which took place at 7:15 a.m., as Foley, 60, was leaving for work, smacked of premeditation.

Officials said the most likely culprits were local militants angered by U.S. policy in the region and motivated by attacks in Kuwait, Yemen and Bali.

Jordanian security sources dismissed a claim of responsibility sent by a virtually unknown group, the Nobles of Jordan, to Al-Quds Al-Arabi, an Arabic newspaper published in London. But both Jordanians and Western diplomats said it was unlikely that any large, organized group of extremists like al-Qaida could have a cell operating here.