Americans who have been serving in the Rhodesian Army as "professional soldiers" are now wondering how they will be treated by the U.S. government when they return home.

While in Rhodesia last week on a tour of southern African countries, aides of Sen. George McGovern (D-S.D.) were approached by one such American who said he was representing 10 others worried about whether they will be prosecuted for fighting in a foreign army or lose their standing in the U.S. Army Reserve.

The American, Capt. William (Lim) Atkins, 34, said he and his colleagues wanted Sen. McGovern, who may take over the Africa subcommittee of the Senate Foreign Affairs Committee, to find out what well happen to them when and if they go back.

"There is no law we have broken just by our participation in the Rhodesian Army," Atkins said in an interview." But there is that threat that we could lose our ctizenship."

Of special concern to these Americans, many of whom are officers or noncommissioned officers in the Rhodesian forces, is that their secret clearance in the U.S. Army Reserve will be lifted and they will not be able to get back in and quality for retirement benefits.

Persons familiar with U.S. law in such situations note that it is very difficult in general to lose U.S. citizenship, but said criminal statutes and citizenship issues are involved and each case would have to be judged individually.

Atkins was dismissed from the Prince George's County police froce in February 1975 after a police review board found that he had unlawfully arrested a person, had failed to report porperty taken during the arrest and had lied to a superior during a departmental investigation of the incident.

[An administrative hearing board earlier had said Atkins was not guilty of misconduct in an incident in which he shot and killed a Seat Pleasant man in the man's bedroom after responding to an emergency call placed by the man's wife.]

Once edtimated to number around 400, there are thought to be no more than 100 and possibly as hew as 50 Americans still serving in the Rhodesian armed forces. Atkins said he did not know the exact figure and that he was only representing 11 officers and NCOs in his appeal to Sen. McGovern.

He met briefy with Jeff Smith, an aide to McGovern, in the lobby of the Meikles Hotel but did not see the senator. Smith said he told Atkins he would have to write a letter before the senator's office would take up their case with State Department and U.S. immigration officials.

Atkins said in an interview that he and several of his colleagues had already been "harassed" by FBI and State Department officials while on leave in the United States.

Atkins, who served from 1972 to early 1975 in the Prince George's County police force, alleged that the harasment was aimed partly at getting him others like him to work for the Central Intelligence Agency in Rhodesia.

He said that while on leave in the United States in November 1977 he was called in on three separate occasions by the State Department and questioned by six different persons. He said $11,200 in his acount in a Prince George's County bank was seized on the grounds that the money had been earned illegally in Rhodesia and that he had not paid U.S. taxes on it.

After threatening to go to court, Atkins said he got his money back five months later. He sais the money had been earned before he left to join the Rhodesian forces.

Atkins, who holds the rank of major in the U.S. Army Special Forces Resrve, alleged that he had been threatened by the State Department officials that if he did not cooperate "there were things they could do."

"They were trying to get me to work for them," he said, referring to the CIA. "Basically, they tried to recruit me."

He also alleged that he was further "harassed" by a local CIA agent when he returned to Rhodesia in March 1978.He said he thought the agent partly had a persoual grudge against him, but that 70 percent of the reason for his difficulties here was "professional."

He said that five guns he had brought back to Rhodesia with him were seized by the police at the instigation of an American living in Salisbury who he said was well known among other Americans to be a top CIA agent.

Americans like Atkins, who is a helicopter pilot and has had 3 1/2 years of experience in U.S. Army Special Forces in Vietnam, have been a valuable asset to the Rhodesian Army, which is particularly strapped for such highly trained personnel.

While admitting there was a fringe group of Americans who came to Rhodesia as "soldiers of fortune," or mercenaries, he said many like himself were here out of a desire to halt the "Communist threat" and were professionals paid at the regular Rhodesian pay scale for their rank.

Atkins, holding the rank of captain, said he gets the equivalent of about $725 a month, while he would be getting around $1,250 in the U.S. Army. He denied that there were any special "perks," or fringe benefits, for foreigners serving in the Rhodesian armed forces or that he could send any of his earnings abroad in hard currency.

He said he had worked in Saudi Arabia for one year for a $30,000 salary and that it was certainly not for money that he had come to fight in Rhodesia.

"I do feel strongly there is a threat by communism to undermine that American way of life, that democratic free way of doing things that you cannot do under communism," he said.

He feels that the blacks in the biracial transitional government ruling Rhodesia now are committed to building a "European-style society" that is worth fighting for.

"I can live under a black government if it maintains that image it has now," he said, adding that right now he intends to serve out his three-year contract with the Rhodesian forces that ends in February 1980. "I have no intention of going back to the United States."