Two suspected 'homegrown' terrorists have been arrested for allegedly plotting to attack a New York synagogue.

Officers seized the pair, reported to be Mohammad Mamdouh and Ahmed Serhani, as as they allegedly tried to buy guns and grenades in exchange for drugs.

It is the first terror plot uncovered in Manhattan since Osama Bin Laden was killed almost two weeks ago, and will raise fears in a city already on high alert for reprisals.

One of  the men allegedly bragged about his plan to attack a synagogue just moments before anti-terrorism officers swooped.

Mamdouh, of Moroccan descent and Serhani, of Algerian descent, were arrested late last night. Both are U.S. citizens and already had weapons in their possession, police said.

Serhani, in his 20s, has a criminal record for narcotics, and was allegedly trying to sell drugs to fund the gun deal.