The Maryland-National Capital Park and Planning Commission has adopted a strict policy barring any transactions with firms that have business ties to South Africa, an action that could affect up to $7 million annually in purchases for the bicounty agency.

The commission's executive director, Thomas H. Countee, said yesterday that the 10-member commission, acting Wednesday, gave its secretary-treasurer until Sept. 30 to detail the impact of the new policy on the agency's $70 million budget. The commission oversees zoning matters and recreation facilities for Montgomery and Prince George's counties.

The commission's separate retirement board, which handles $55 million in pension investments, will take up the divestment issue at its meeting next week, Countee said.

"I'm confident that we can find alternative supplies and products in most cases," Countee said of the board's decision.

The commission rejected a recommendation that it exempt from the sanctions those companies that adhere to the Sullivan Principles, a set of guidelines under which companies hire, pay and assign workers without discriminating.

The action is a protest of apartheid, the system of racial segregation that is law in the Republic of South Africa.

Montgomery County Executive Charles Gilchrist instructed the county's insurance company in March not to use county pension funds in South African-related investments. In Prince George's, the County Council recently passed a nonbinding resolution that condemns apartheid.

Edward Navarre, the park and planning commission's secretary-treasurer, said that perhaps 5 to 10 percent of the commission's annual budget will be affected by the new purchasing restrictions.