More than 400 inmates at the Virginia State Penitentiary in Richmond have petitioned Gov. John N. Dalton to remove the warden there and investigate "undue and inhumane conditions" at the facility.

The prison, a massive, aging structure built in 1800, currently houses about 900 inmates. About half of them signed the petition accusing Warden J. P. Mitchell of showing little concern for inmate rights.

The inmates complained that Mitchell has violated state law and institutional guidelines. They also alleged that prison parole policies are misused and that inmates are not adequately prepared for life on the outside once they are released.

The petition, which was addressed to Dalton, the Department of Corrections, the attorney general, the State Crime Commission, the State Parole Board, and the news media, was being studied yesterday by the corrections department.

"It's a semiannual occurrence for inmates to get up a petition to ask for the firing of the warden," said department spokesman Wayne Farrar. Although conceding an investigation would "likely find some valid complaints," Farrar said the department's director, Terrell Don Hutto, "is not considering firing the warden."

Farrar attributed much of the problem to a recent tightening of the rules governing visitors to social functions at the prison. He said lax regulations had led to incidents of illegal drug and sexual activity inside the facility.

Lewis Hurst, executive director of the Crime Commission, said he had asked prison ombudsman, C. Hoy Steele, to look into the complaints outlined in the inmate petition.