A former U.S. government employee, emerging as a mystery man in reports of fresh Reagan administration efforts to free American hostages in Lebanon, denied he tried to negotiate a prisoner release with Iranian figures.

Richard Lawless, president of a trade and investment consulting firm, on Wednesday sought to refute assertions by former Iranian President Abolhassan Bani-Sadr that he has been working on the hostage problem behind the scenes on behalf of the administration.In doing so, Lawless, 44, echoed statements made earlier by White House and State Department officials seeking to knock down Bani-Sadr's allegations. Administration spokesmen have said Lawless is not a government employee and has not been carrying out any kind of mission on behalf of the United States.

Meanwhile, a member of the U.S. State Department said officials see no sign that other American hostages in Lebanon may be freed in the wake of a captive's release earlier this week, .

The U.S. official, who went to Wiesbaden, West Germany, with a State Department team to debrief the freed hostage, also said Wednesday the Reagan administration assumes the kidnappers are financed by Iran.

Doctors here said freed hostage Mithileshwar Singh, a 60-year-old Indian citizen and resident alien of the United States, was in good spirits. However, they said he faces tremendous stress as a result of his 20-month ordeal.

U.S. Air Force spokesman Master Sgt. Charles Fick said Thursday that Singh, resting at the Air Force's Wiesbaden hospital, had decided not to hold a press conference.

President Reagan and his aides steadfastly denied all reports that the U.S. government is negotiating directly with the Iranians on the hostage situation.

Speaking through the co-owner of his firm, U.S.-Asia, Lawless said: "I categorically deny and state for the rec-ord that I am involved either directly or indirectly in any discussions or negotiations with any party related to attempts to secure the release of hostages in Lebanon."

Lawless also said, "I have never in my entire life had any direct or indirect contact with any Iranian government officials or any Iranian nationals claiming to represent the Iranian government or any Iranian related interests."

On Tuesday, Bani-Sadr said in Paris that Lawless had negotiated in behalf of Vice President George Bush with a representative of Iranian Parliament Speaker Hashemi Rafsanjani, in an attempt to get American hostages liberated.