Undated (AP) _ Donations to the Salvation Army have jumped in the last week, in part because of publicity about decreased donations coupled with increased demand for aid, a spokesman said Monday.

''Because of the added publicity, the funds are starting to come in at a much quicker pace than the week before,'' Lt. Col. Leon Ferraez, the Salvation Army's national communications director, said from the group's headquarters in Verona, N.J.

''The people have been responding magnificently,'' he said.

''I just don't think anyone is going to be turned away,'' Ferraez said. ''We're just going to try and pay our bills at the end of the month. We operate on faith, and we have had some anxiety this month.''

He stressed that ''the demand for help has not decreased'' in the last week. Requests for aid have surged this year, by as much as 63 percent in the Northeast.

Last week, he estimated that mail donations in the early days of the Christmas fund-raising season were down 8 percent, and that kettle donations nationwide were up but not enough to make up for the mail shortfall. Now, he said, he hopes that the wave of donations will bring the year's total about equal to or even above last year's $50 million.

In at least one city, last-minute applicants for help will probably not receive assistance Tuesday. In Fort Wayne, Ind., Maj. Paul Fuqua said his unit could not assist as many families as it had hoped. He said 1,325 families sought help, compared with 1,100 last year.

''We had many more clients than we ever had anticipated we'd have,'' Fuqua said. ''At noon (Tuesday) we are closing the door and helping only those that are inside.''

Fuqua said the Fort Wayne unit had raised only $123,000 of a goal of $150,000.

But Maj. Ralph E. Thomas of the Rhode Island Salvation Army in Providence said Monday that $3,475 in kettle donations came in Friday, the best single day in his memory. Saturday also was outstanding, but the donations had not been counted, he said.

Before the surge, requests for help in Providence were up 3 percent while contributions were down 12 percent, Thomas said. In Newport, requests were up 84 percent while donations were down 30 percent.

The Salvation Army in Albuquerque, N.M., issued a plea for assistance Friday. ''We ran out completely, totally. We had no food, no toys, no nothing,'' said Salvation Army Supervisor Johnny King.

He said Monday that hundreds of people dropped off toys, food and clothing over the weekend.

In Knoxville, Tenn., Maj. Herbert Bergen, commanding officer of the Salvation Army branch there, said Monday that donations have picked up and the group is within $15,000 of its goal.

''The public has really been good,'' he said. ''They have responded in a beautiful way, and we appreciate it.''

In Cleveland, the Salvation Army stopped accepting formal applications for holiday aid Dec. 16 because of a lack of funds. But officials said Monday they kept records on 800 people who sought aid after the applications were cut off and believe they have received enough in donations in the past week to help them all.

One of the first Salvation Army branches to raise the possibility of turning away people unaided was in Boston. But donations were so good after that announcement was made Dec. 16 that ''all of a sudden they have a problem of where they're going to store the food,'' Ferraez said. ''It's been remarkable.''

The Salvation Army, a religious group that is organized like a military unit, has about 1,000 large centers to aid the needy and homeless, plus 9,000 smaller office that can refer people to the larger centers, the national spokesman said.

Each branch conducts its own fund-raising and its own aid projects, so precise figures on donations are not available, Ferraez said.