An attorney for Daniel Minchew, former aide to Sen. Herman E. Talmadge (D-GA.), said yesterday that Minchew gave documentary evidence to Senate investigators supporting his claim that Talmadge knew of an illegal secret bank account set up here in the senator's name.

Meeting with reporters after three days of closed-door testimony by Minchew before the Senate Select COmmittee on Ethics, Robert Fierer, Minchew's Atlanta attorney, said three large briefcases full of supporting material had been turned over to committee investigators.

Nearly $39.000 in illegal Senate funds and campaign contributions to Talmadge were funneled through the secret account in the Riggs National Bank while the account was active in 1973 and 1974, according to sources close to the investigation.

Talmadge has emphatically denied knowing of the bank account until recently. He said it was set up and run by Minchew without his knowledge or approval.

The 22-year Senate veteran is under investigation concerning the secret account of his other financial affairs by the ethics committee, the Internal Revenue Service and a federal grand jury here. He has denied any wrongdoing.

Minchew, who was Talmadge's senior aide until 1974, said he did open the account and sign checks and other bank documents with Talmadge's automatic signature pen. But he said yesterday through his attorney "whatever was done, was done for or on behalf of Sen. Talmadge and with his knowledge or approval."

The documents turned over to the Senate investigators yesterday "would support Mr. Minchew's position," Fierer told reporters.

Carl Eardley, the Senate committee's special counsel said yesterday that the committee would seek additional testimony from witnesses here and in Atlanta because of Minchew's testimony. Eardley said Talmadge would also be questioned for a second time, probably within the next two weeks.

In a related matter, a spokesman for Talmadge denied that he had pressured the Senate Watergate Committee for a speedy end of its probe into political payoffs by the dairy industry at the same time he received two $5,000 contributions from the dairymen. One of the contributions was deposied for a while in the secret account, sources have said.

Gordon Roberts, a spokesman for Talmadge, said no unusual pressure was involved and that the committee closed out its probe of the dairymen because it was taken over by the Justice Department, not because of pressrure from Talmadge.

Roberts said Talmadge did not know about the dairymen's contributions until the Senate Watergate investigation was completed.

Samuel Dash, former chief counsel to the Watergate committee, said yesterday that, while Talmadge did seek a quick conclusion to the Senate probe in 1973, he did not interfere with its investigation. "At no time did he suggest we cut off development of any evidence," Dash said.