LOS ANGELES (AP) _ Immigration officials overnight seized 69 illegal aliens about to board the same cross-country flight on which 79 undocumented immigrants were taken into custoday the night before, authorities said.

The 69 were trying to board an Eastern Airlines flight to New York by way of Atlanta, said Immigration and Naturalization Service spokesman Joe Flanders.

He said 54 were from Mexico, seven from El Salvador, four from Colombia and four from Guatemala. Most will be allowed to go home or request a deportation hearing, he said.

Flanders said one man was arrested and may have been the principal smuggler.

On Monday, authorities seized 79 illegal aliens during Flight 80's 5:35 a.m. stopover in Atlanta, acting on tips from airline sources and someone who often traveled the route and became suspicious of fellow passengers.

Investigators believe illegal aliens have been aboard the Eastern overnight flight nearly every day for the past 30 days, said Tom Thomas, an INS spokesman in Atlanta.

Thomas said the flight might have been used because no plane tranfers are involved and rates might have been cheaper.

''There's a commuter who regularly flies from Los Angeles to Atlanta who called our office. ... and said, 'Hey, it seems there's an awful lot of Hispanic people who fly this flight. You might want to check into it,''' Thomas said.

Thomas said some of the aliens indicated they had paid up to $4,000 for a package, but authorities don't know what that deal included other than air fare from California to New York. The package could have included living arrangements, phony documents and a job, he added.

On Monday, the cheapest fares available for the flight were $433 to $577, including taxes, according to a travel agent.

One of the 79, Elias Quevedo-Gonzalez of Pachalun, Guatemala, said he borrowed $1,400 from neighbors to make the trip so he could earn money in the United States to send back to his wife and seven children.

''About four people in my town have done that, and when they came back I could see their families were much better off,'' the 39-year-old man said. ''They had better clothes and good food.''

Thomas said Eastern has cooperated fully in the investigation.

''We don't in any way connect Eastern and don't want to intimate that they were even remotely involved at this point,'' he said.

In Miami, Eastern spokeswoman Virginia Sanchez said, ''All I know is that the INS had told us they'd be monitoring a flight this week and, of course, we cooperated with them.''

In addition to Guatemala, the aliens taken off Monday's flight came from Mexico, the Dominican Republic, El Salvador, Honduras and Ecuador, Thomas said. He said they would be transferred to INS processing facilities in Florida and Texas for deportation.

But one of the aliens, Juan De La Cruz-Rodriguez, 34, said he would do whatever he could to stay in this country ''because if I go back, they'll put me in prison. They'll kill me if I don't pay what I owe.''

De La Cruz-Rodriguez, who said he was trying to make money to send to his wife and three young sons in the Dominican Republic, said a smuggler in Mexico helped him and about a dozen others cross the border, then arranged to have them transported by flatbed truck to Los Angeles.

''I always had the image of America having a lot of money and a lot of wealth, and that I could find work without any problem,'' he said.

He said he sold his truck to raise part of the money and gave the smuggler almost $1,000. Holding up a quarter, he said, ''That's all I have left.''