South Africa today released on bail five mercenaries who fled to this country in a hijacked airliner last week after staging an unsuccessful commando raid to overthrow the government of the Indian Ocean island nation of Seychelles.

The five men laughed and joked with prosecutors during a brief session in a Pretoria magistrate's court, which charged the five with kidnaping, but made no mention of the hijacking, the coup attempt or the Seychelles government request for extradition of 44 commandos who escaped to South Africa after the raid.

The other commandos were freed without charges last night by South African police, who refused to reveal the identities of the mercenaries, earlier reported to include former members of elite South African military units.

In Washington, the State Department issued a statement criticizing the South African action and noting that "South Africa is a party of the Hague Convention against hijacking, which obligates the government of South Africa to submit for prosecution or to extradite persons accused of unlawfully seizing aircraft. The United States has made its views of this issue known to the South African government."

In the Seychelles, President Albert Rene said that the releases confirmed his charges that South Africa was involved in the coup attempt against his socialist government. Seychelles officials meanwhile paraded before reporters two men with bruised and swollen faces said to be among five mercenaries captured during the attack Nov. 25 and 26.

The releases followed a Cabinet meeting of the Pretoria government yesterday that was called to give "urgent attention" to the Seychelles coup attempt. A South African opposition leader, Brian Bamford, of the Progressive Federal Party, called the action "scandalous" and said it "will add fuel to the suspicions that people have voiced overseas about South Africa's alleged involvement."

"In my 25 years of law I have never heard of a case where you have a group of conspirators and the state charges some of them and releases others," Bamford said.

The court's decision to bring kidnaping charges instead of hijacking counts against the men added another twist to the already bizarre case.

A U.S. official, who declined to be identified, said the South African handling of the mercenaries was "very surprising to all of us" because South Africa "seemingly countervened its own policy" of outspoken opposition to hijacking and could give the impression of "being soft on terrorism."

Among the five who appeared before Magistrate Cornelius Van Loggerenberg in a cramped, makeshift courtroom set up in an office building, was the legendary mercenary leader Michael (Mad Mike) Hoare, 62, who apparently was the leader of the Seychelles expedition.

The others were identified as Peter B. Duffy, 40, British; Charles Glen Goatley, 27, Zimbabwean; Tullio Moneta, 42, a naturalized South African, and Kenneth H. Dalgliesh, 32, British.

The five men were dressed in casual clothes for their brief court appearance. They appeared relaxed and unworried, exchanging jokes with the policemen guarding them as they stood in the tiny wooden dock surrounded by journalists and other spectators.

Nearby stood four young black men handcuffed together, waiting for their cases to be heard.

Hoare, a small man with a tanned, lined face rimmed with a sparse, gray goatee, looked like he might have been a college professor rather than a mercenary. Around his neck he wore his trademark -- a monocle on a long black string. He declined to comment to the press.

During the 10-minute proceedings, state prosecutor Paul H. Fick requested the court to release the men on bail. He did not detail any of the events leading up to the charge nor identify the victim or victims of the kidnaping. Outside court, he declined to explain why the men were charged with kidnaping rather than hijacking.

Hoare's bail was set at $10,500, which he paid immediately with a stack of rand notes produced by his nephew. The others paid $5,250 each.

The five accused are required to report to their local police stations once a week at designated times. The court put off hearing the case until Jan. 7.

Police Minister Louis Le Grange said that police were satisfied that only five of the mercenaries should be charged "at this stage," according to the South African Press Agency. He said some of the released men might be used as state witnesses or charged at a later date.

Fick said the kidnaping charge against the five was "provisional" and other charges could be laid against them later.

Under South African law, kidnaping has no stipulated penalty, whereas hijacking carries a statutory minimum penalty of five years and a maximum of 30.

Earlier this year, the all-white legislature, concerned about possible hijackings of South African planes by blacks who oppose apartheid, tightened regulations to prevent and cope with air piracy.

During the parliamentary debate, Minister of Transport Hendrick Schoeman boasted that South Africa had signed three international conventions against "unlawful interference with civil aviation" and had a laudable record in enforcing international regulations for air safety.

Some observers speculated that the police refused to identify the other mercenaries because most are believed to be recently discharged from Rhodesian or South African units that are often used in cross-border operations and some of the mercenaries may still be listed as active members of those units.

Barry F. Gribbin, an American believed by the U.S. Embassy here to be among those released without charges, could not be reached today at the house he shared with friends in a northern suburb of Johannesburg.