Ferris & Co., a District-based brokerage house, announced an agreement yesterday to take over and service the 3,000 Washington-area clients of John Muir & Co., the New York company that shut its doors last week.

The announcement followed negotiations with attorneys for the court-appointed trustee for the defunct brokerage firm and with representatives of the Securities Investors Protection Corp.

George Ferris Jr., chief executive of Ferris & Co., said the company has about three weeks to accept or reject the Muir accounts if the plan to assume the accounts is approved by a court involved in the liquidation. "We can after talking to the people determine whether their attitude is such that they would be happy working with the company's investment philosophy," Ferris said.

Ferris said that although the company has not studied the accounts to determine whether any "discrepancies" exist, any problems with the accounts would be the problem of the Muir company's trustee. Ferris & Co. also is taking responsibility for a Georgetown office previously occupied by Muir. Ferris said the agreement does not call for hiring Muir employes.

The accounts have been frozen, although Ferris said he expects the freeze to be lifted next week. The Securities Investors Protection Corp. protects these accounts against losses of up to $500,000 in assets.

The closing of Muir came as a result of the firm's failure to meet federal net capital requirements, which require investment companies to have a certain ratio of liquid assets to obligations.

Muir & Co. operated offices in McLean and in the District. Their clients are asked to call Ferris offices in the District, McLean, Rosslyn or Bethesda.