Salvation Army officers in several cities are under criminal investigation for allegedly receiving illegal kickbacks from a Philadelphia second-hand clothing dealer, according to law enforcement officials.

The Salvation Army officers allegedly received the improper payments from Dumont Export Co. from 1970 until May 1983 in return for providing the Philadelphia clothing merchant with a regular supply of castoff clothing that even the charity's thrift shop managers no longer wanted.

Dumont then shipped the old clothes to Third World and European countries where it was resold as wearing apparel.

The investigation by the U.S. Customs Service and the U.S. Postal Service was disclosed when criminal conspiracy and mail fraud charges were filed earlier this week against Dumont and its two owners, Harry and Jerald Usatch.

According to a criminal information filed in U.S. District Court in Philadelphia by the U.S. Attorney's Office, the clothing dealer and its owners are accused of one count of conspiring to make false statements to U.S. Customs and one count of mail fraud.

Stephen Wehner, the federal prosecutor in charge of the case, said the mail fraud count accuses Dumont and the Usatches of "making payments to Salvation Army officials in return for securing a steady supply of used clothing for sale overseas."

The prosecutors said in a statement that Dumont "defrauded the Salvation Army out of the loyal and faithful services of some of its officials to ensure a steady supply of quality rags to their export market" and defrauded shipping companies of $443,000 by understating the value of shipments.

Wehner said the investigation was continuing but that he could not discuss its substance. He said the defendants had not yet entered a plea on the charges and no hearing date has been set.

He would not disclose what cities were involved in the investigation.

Dumont Export Corp. and its owners refused to comment on the charges.

Frances Weiss, assistant director in the communications department of the Salvation Army's national headquarters in New York, said that the Army regarded the Philadelphia investigation as a "pending legal matter" and was referring inquiries to its legal counsel. Telephone calls to the attorney's office were not returned.

Weiss said that the Salvation Army had 5,000 uniformed officers in the United States and employed about 25,000 people nationwide.

The Salvation Army, founded in London in 1865, is a worldwide Christian religious organization with a military structure that provides food, shelter and clothing to the needy.

One well-known feature of the Army is its streetcorner musicians, who play instruments and sing and preach the gospel.

Weiss said the practice of selling unwanted thrift shop clothing to dealers for resale in underdeveloped countries has been common for years. But she said she had "no knowledge" of any Salvation Army officers receiving personal payments from clothing dealers.

David Warren, special agent in charge of Customs' criminal investigations office in Philadelphia, said yesterday that "several senior officals of the Salvation Army are still under investigation by U.S. Customs and the Postal Inspection Service" in connection with the alleged receipt of kickbacks from Dumont Export.

According to sources familiar with the case, Customs and Postal Service investigators at one point investigated as many as 30 Salvation Army officers and employes for receiving the payments.

The criminal information alleges that the Usatches "purchased money orders in a false and fraudulent name and mailed these money orders to said officials of the Salvation Army, the amount of payment being based upon the weight of the rags sold by the Salvation Army to the Dumont Export Corp."

The investigation now has been narrowed to concentrate on five to 11 of the more senior Salvation Army officials who have been implicated in the scheme.

Sources indicated that the officers still under investigation are assigned to Salvation Army offices around the country.

Government investigators said they believe Dumont Export paid both the Salvation Army itself and local Army officers for the castoff clothing, which it collected and shipped overseas.

The Army was paid by the pound for clothing it turned over to Dumont, and the Salvation Army officers allegedly received a smaller per-pound fee for each shipment collected in their territories.

Investigators said that some Army officers who received the payments turned them back to the charity, but that several recipients allegedly pocketed the kickbacks.

Federal officials said Dumont shipped the clothing it obtained from the Salvation Army and other charitable groups to such destinations as Nigeria, Bangladesh, Zaire, India, Togo, Benin, Burundi, Italy and France.

Officials said that although clothing was obtained from several charities in the United States, only Salvation Army officers are under investigation for receiving kickbacks.

One investigator said that the U.S. Customs Service discovered the alleged kickback scheme while examining cargo consignments outbound from Philadelphia as part of "Operation Exodus," the Reagan administration's much-touted campaign to crack down on smuggling of U.S. high-technology equipment to the Soviet bloc.

According to this account, Customs officers became suspicious about a shipment labeled as "auto parts" that was being sent overseas by Dumont.

Instead of discovering sophisticated computers, however, Customs officials found a load of old clothes, which made them even more curious about the shipment.

Investigators now believe that Dumont mislabeled its clothing shipments to evade import controls in countries such as Nigeria, which ban clothing imports to encourage development of their own garment industries.