A suspect wanted over a homemade bomb blast outside a Los Angeles-area synagogue last week has headed for New York, traveling across the United States by Greyhound bus, police said.

Ron Hirsch, described as "extremely dangerous," boarded a bus bound for the East Coast last Thursday, within hours of the early-morning explosion at the Chabad House synagogue in Santa Monica.

"Investigators confirmed that a man known as J. Fisher, a known alias used by suspect Ron Hirsch, purchased a Greyhound bus ticket to New York that was originally scheduled to arrive Sunday, April 10th," said a statement.

"There are at least ten destinations in between Los Angeles and New York," it said, adding that video surveillance suggests Hirsch got off the bus in Denver, "and may have further deviated from his original route."

Hirsch -- who detectives had previously said used the alias Israel Fisher -- is believed to have family in New York, said the joint statement by the Federal Bureau of Investigation (FBI) and Santa Monica Police.

Detectives issued a mugshot of the heavily-bearded suspect late Friday, and were working on releasing surveillance camera footage believed to show him on the east-bound bus.

"Based on his suspected involvement in this incident, Hirsch is considered extremely dangerous," said the statement, adding that an unspecified reward is available for information leading to a conviction.

"Hirsch is known to frequent synagogues and Jewish community centers seeking charity from patrons," and is "currently being sought on state charges of possession of a destructive device and unrelated local charges," it added.

Police stepped up patrols around local synagogues and Jewish centers after the blast, which propelled a 300-pound (135 kilo) metal post cased in cement into the air, landing on the roof of a neighboring house.

Nobody was injured in the explosion, which triggered initial reports of a pipe bomb. Police then said the blast was due to "some type of mechanical failure," but then confirmed late Friday that it was an explosive device.

Some 100 people were evacuated following the blast, which also shattered windows and damaged an outside wall of the synagogue.