NEW ORLEANS (AP) _ The immigration amnesty center in New Orleans is staying open late to make it easier for illegal aliens to apply for amnesty before the program ends, the latest in a number of incentive measures across the nation.

''Time is running out,'' said John B.Z. Caplinger, district director for the U.S. Immigration and Naturalization Service. ''The legalization program ends May 4, and we want to do everything possible to ensure that any person eligible for amnesty has the opportunity to apply.''

So until then, the New Orleans Legalization office will be open from 8 a.m. to 6 p.m. Monday through Friday and 8 a.m. to 4:30 p.m. Saturday.

The program gives people who came into this country without the proper permits before Jan. 1, 1982, a chance to stay legally and work toward U.S. citizenship. More than 1 million aliens already have applied across the country, about 1,500 of them in New Orleans.

Illegal aliens who have worked as seasonal agricultural workers will have until Nov. 30 to apply. All others must apply before May 4.

In Maryland, the INS has extended the hours of its Baltimore legalization office to 8 p.m. on Tuesdays and Thursdays and has opened the office on Saturdays from 8 a.m. to noon, said Louis D. Crocetti Jr., deputy director of the INS in that city.

The INS even plans to rent an airplane to fly over Baltimore's Memorial Stadium on opening day of baseball season next month. The plane will pull a banner reminding aliens to apply for amnesty before the deadline, Crocetti said.

Elsewhere, a banner reminding people of the amnesty program was included in a parade ringing in Chinese New Year in Los Angeles last month.

In McAllen, Texas, INS employee Art Zuniga wrote a song in Spanish, ''Amnistia,'' to promote the amnesty program, and local radio stations agreed to play it. Zuniga, 38, who grew up in the lower Rio Grande Valley in a family of farm workers and writes songs for a country-and-western band, said he wrote the song because he understands people who come to this country seeking work.

The INS also plans to start putting fact sheets in tortilla packages around Texas, with the cooperation of several bakeries.

The agency also built a parade float for the Washington's Birthday celebration in Laredo, Texas, and Boy Scouts will be used to distribute leaflets door-to-door in the impoverished unincorporated rural areas of the lower Rio Grande Valley known as ''colonias.''