PHILADELPHIA?The FBI told passengers on a flight forced to return after takeoff that their plane was rerouted because several passengers of Middle Eastern descent had purchased one-way tickets with cash that day, passengers said Monday.

In Houston, meanwhile, several staff members from the Saudi Arabian Embassy were detained while trying to board a flight at Bush Intercontinental Airport on Sunday. They were released after their identities were confirmed, Houston FBI spokesman Bob Doguim said Monday.

FBI spokeswoman Linda Vizi would not confirm the accounts about Sunday’s flight from Philadelphia to Orlando, Fla., but said the suspicious passengers were interviewed and released early Monday without being charged.

“We were able to determine their travel plans were legitimate and their identities were legitimate,” Vizi said. “We have checked out the documentation of these individuals, and everything is in order.”

Passengers Glenn Mattes, 48, and Jack Clark, 55, said FBI agents also told passengers that two other planes, one in Houston and the other in Baltimore, were grounded because passengers of Middle Eastern descent had bought one-way tickets that day with cash.

Vizi would not comment on that account.

Pete Gulotta, an FBI spokesman in Baltimore, said his office was asked to check the names of seven Middle Eastern men boarding a plane for Dallas at Baltimore Washington International Sunday morning. After checking, airport officials were told there was no reason to detain the men, Gulotta said.

“There was not any suspicious activity, there was no reason to hold these people as far as we were concerned,” Gulotta said. “All we did was check some names.”

Mattes and Clark were among 134 people aboard the US Airways flight from Philadelphia to Orlando, which the FBI acknowledged was turned around Sunday because some passengers were thought to be engaged in “suspicious activity.”

The individuals were taken off the flight without incident and questioned by the FBI, Vizi said late Sunday. Bomb sniffing dogs found no explosives, she said.

Federal air marshals contacted the FBI about the passengers, Vizi said. US Airways Flight 335 was ordered to return to Philadelphia and landed at 7:05 p.m., less than an hour after takeoff.

It was taken to the old international terminal of Philadelphia International Airport, which is seldom used and is far from the main terminals.

“We landed and we’re sitting around almost two hours. Finally, they said the FBI’s coming on the plane and that’s when the wave of emotion hits everyone,” said Clark, of Blue Bell.

Passengers said four or five people had been acting suspiciously.

Clark said that after the suspicious passengers were removed, an FBI agent told the remaining passengers about the Baltimore and Houston flights and said the other planes had been stopped before taking off.

The remaining passengers went through security screening and were sent to Orlando.

“From an abundance of caution since Sept. 11, we want to make sure that everyone gets to their destination safely,” Vizi said Sunday night.

In Houston, the four or five embassy staff members were detained after airport security noted that none had checked luggage for the Baltimore bound flight, Doguim said. They were released after they produced diplomatic passports, he said.

The men said they had come to Houston on a day trip for the visit of Saudi Crown Prince Abdullah, Doguim said.