Former tennis champion Arthur Ashe is among the group of investors seeking a baseball expansion franchise for Northern Virginia, the group's leader, Mark Tracz, said yesterday. However, a "substantial" amount of the group's money will come from two family trusts, according to a Washington investment banker representing the families.

"One of them will hold a majority interest," said Jim Valentine, who added he also will be an investor.

Valentine declined to identify the families but said both have considerable national holdings. The enterprises of one family are based in the District and those of the other are based in Northern Virginia, Valentine said.

Both families will remain limited partners. An entity headed by Tracz and involving Ashe, a Richmond native who became the first black male Wimbledon champion, will control the group as general partner.

In addition to Ashe, now a writer and businessman living in New York, Tracz said his group includes the founders of one of the Washington area's largest real estate firms, the president and chief executive officer of a Baltimore bank, two Northern Virginia attorneys and the owner of an area venture capital firm.

Tracz's group, Capital Region Baseball, is hoping to obtain one of the two teams the National League will add in 1993. Capital Region Baseball would like initially to locate a club at RFK Stadium, then move to a new stadium in Northern Virginia.

Washington developer John Akridge is heading Metropolitan Washington Baseball, a separate group that would like to locate a club permanently at RFK Stadium.

Both groups have said they will meet the Tuesday deadline for submitting a response to the NL Expansion Committee's questionnaire along with a $100,000 deposit on the $95 million entry fee.

Among Tracz's investors: P. Wesley Foster Jr., president of Long & Foster Realtors; Henry A. Long, Foster's former associate who is now president of the Henry A. Long Co., a commercial development firm; Sterling Bank and Trust Co. President Arthur Silber, who is also chairman of the board of the Class A Prince William Cannons; Thomas Pumpelly, former owner of National Tire Wholesale Inc. who now owns PCI Financial Group; attorneys Paul Shiffman and Jerry Phillips.

Tracz said his group has obtained commitments from others he declined to name, has $100 million in cash and is in a position to obtain $25 million to $50 million more, the amount believed necessary to pay the entry fee and start-up costs.

"We'll be adding others," said Tracz, who declined to say how much money each member of his group has invested. One group member, developer William Bryant, has said he is prepared to commit $5 million.

Bryant will join Tracz and Ashe in the general partner entity. The controlling group's other members will be Phillips, Silber and attorneys Ira Saul, Bart Fisher and Phil Tierney.

Tracz said his group was not planning to bid for the Montreal Expos, which owner Charles Bronfman wants to sell.