MANAGUA, Nicaragua--Sam Nesley Hall, a self-described freedom fighter and brother of a U.S. congressman, will be released within hours because the government decided not to press spy charges, the state-run radio station said Tuesday.

In a brief announcement, the leftist Sandinista government's Voice of Nicaragua said the Foreign Ministry decided to free Hall immediately, apparently to family attorney Gary Froelich, of Dayton, Ohio.

Froelich arrived in the Nicaraguan capital Monday to arrange local counsel for the prisoner, who is a brother of Rep. Tony Hall (D-Ohio).

The Sandinista government has said Sam Hall, 49, needs institutional care not available in Nicaragua.

Officials declined to specify Hall's illness, although government sources who spoke on condition of anonymity said he suffered from a mental disorder. There is a mental hospital in Managua, but as with the rest of the nation's health care system, it is severely limited.

Hall was arrested Dec. 12 at Punta Huete air base, 13 miles northeast of Managua, with maps and sketches of the airfield, crudely drawn on hotel stationery, stuffed in his socks, the Sandinistas said at the time.

In subsequent interviews, Hall denied he was working for the U.S. government but said he was paid $12,500 for his selfproclaimed secret mission and worked for a previously unheard of organization he called the Phoenix Battalion.

Hall said he knew his superiors only as Tinker, Evers and Chance, the last names of a famous Chicago Cubs doubleplay combination early in the century.

He never was formally charged but was held at an undisclosed location for questioning under a national emergency law that gives security agencies wide powers of search and arrest.

Froelich arrived in Managua only minutes after the Foreign Ministry announcement Monday and said he was taken by suprise by the decision.

"We'd like to get him back as soon as possible. We are concerned about what his medicial condition is because it is a very vague description from the information we have," Froelich said before the announcement of a speedy release.

In Washington, Rep. Tony Hall said in a statement, "I am grateful to the Nicaraguan government for promising to release my brother, and I look forward to seeing him when this trauma is all over."