MANILA, Philippines (AP) _ The government filed three more suits Thursday seeking the return of a vast fortune it says deposed President Ferdinand E. Marcos stole from the country.

One accuses a Marcos associate of taking kickbacks from the Westinghouse Electric Corp. of Pittsburgh.

The new civil suits, filed with a special anti-graft court, add 13 defendants to the government's legal attempt to recoup Marcos' alleged ''ill- gotten wealth.''

Each seeks return of the $10 billion the government says Marcos plundered during 20 years in power, plus $2.5 billion in various damages. The three suits raise the total sought so far from more than 100 defendants to $57.7 billion.

One claims businessman Hermino Disini ''obtained staggering commissions from Westinghouse in exchange for securing the nuclear plant contract from the Philippine govermnent.''

It accuses businessman Rodolfo Jacob of executing the contract and claims Westinghouse ''built an inoperable nuclear facility in the country for a scandalously exorbitant amount that included defendants' staggering commissions.''

Westinghouse spokesman Ron Hart said in Pittsburgh the company has acknowledged paying about $17 million in ''commissions'' to two corporations associated with Disini for ''obtaining and impletmenting the contract for the nuclear power plant,'' but added:

''There have been numerous private and governmental investigations and there has been no evidence that any of the commissions were passed through to Marcos or his associates.''

He said two ''authoritative'' agencies, including the Philippine Atomic Energy Commission, had supported the Westinghouse position that the plant is ready to take on nuclear fuel

Hart said the the International Atomic Energy Agency found ''no technical obstacle'' to taking nuclear fuel. Westinghouse has not seen the lawsuit, the spokesman said.

The plant, on the Bataan peninsula northwest of Manila, has not begun operation.

Philippine officials demanded that Westinghouse install more safety features following the 1979 Three Mile Island nuclear accident in Pennsylvania, and this pushed the cost to more than $2 billion. President Corazon Aquino scrapped the project after she succeeded Marcos in a February 1986 civilian-military revolt.

Marcos now lives in exile in Hawaii. Disini is married to a first cousin of Marcos' wife Imelda, who also is a defendant.

The suit also charges Marcos gave Disini the local tobacco filter monopoly and provided unspecified millions of dollars in government funds to rescue troubled companies Disini ran.

In the other two actions, defendants are the Marcoses and 13 business associates, two of whom were named in previous lawsuits. They charge the associates ''acted as dummies, nominees or agents'' for the Marcoses.

The Presidential Commission on Good Government, the panel charged with recovering Marcos' allegedly stolen money, filed a broad civil suit July 16 charging that Marcos and his family looted the nation's treasury, betrayed public trust and brazenly abused power during the two decades he was president.

It charged the Marcoses stole $10 billion and demanded they return that amount plus $12.55 billion in damages, reimburse the commission for $25 million it cost to track the money, and pay unspecified fees and penalties.

The panel has been filing additional suits daily since then, and a commission official said Wednesday that another 30 suits were being prepared.

Commission chairman Ramon Diaz said last week that criminal charges also would be filed soon against Marcos. He did not specify the charges, but they were expected to be similar to those in the civil suits.