An Interior Ministry news release identified the two as Ahmad Salim Swaydan, suspected of involvement an April 2002 plot against the US Embassy in Thailand, and a Yemeni man known only as Altuwiti.
A photo of Swaydan released by Nicaraguan authorities matched that of a man on the FBI's most-wanted terrorist list: Sheikh Ahmed Salim Swedan, a 36-year-old Kenyan indicted on December 16, 1998 for alleged involvement in the bombings that year of US embassies in Tanzania and Kenya.
The US State Department has offered a reward of up to $5 million for information leading to his arrest.
Nicaragua's Interior Department said it had imposed an "immigration alert" at all border posts. But it gave no details about why the alert had been raised.
"We must guarantee that our country is not the scene for the presence of elements linked to international terrorism or organized crime," the department said.
Spokesmen for the US Embassy in Nicaragua said they did not immediately have information on the case.
In Panama, spokesmen for the security and immigration agencies said they had no information.
There have been repeated rumors -- but only a few glimmers of hard, public evidence -- of terrorist suspects passing through Central America.
In the only known confirmed case, US and Panamanian officials said Saudi native and alleged top al-Qaeda operative Adnan El Shukrijumah was in Panama for 10 days in April 2001, five months before the September 11 attacks.
Honduran officials last year reported that two witnesses said they saw Shukrijumah at an internet cafe in the capital, Tegucigalpa. However, US officials say the suspect almost certainly was never there, and local officials eventually backed away from the report.
Honduran Security Minister Oscar Alvarez also had said that al-Qaeda might be trying to recruit Central American gang members to infiltrate the United States, but US officials said there was no evidence of that.