Virginia Republican Senate candidate John W. Warner suggested yesterday that election of his Democratic opponent, Andrew P. Miller, could lead to the appointment of populist Henry E. Howell as a federal appeals court judge.

Warner, in his strongest attack on Miller in the campaign, portrayed the former state attorney general as a "dyed-in-the-wool liberal" and a close friend of the controversial Howell.

Warner made his allegations in a civic club luncheon speech here that was warmly received by an audience of nearly 300 businessmen.

Howell, who defeated Miller in a Democratic primary for governor last year, has expressed interest in gaining an appointment to a federal appeals court, although there are no vacancies for Virginians on the 4th Circuit Court, which sits here.

Citing newspaper accounts of Howell's interest in a judgeship and Howell's well-Known friendship with President Carter, Warner said: "It would sure make it a lot easier for Henry's friend in the White House to carry it (the court appointment) off if Andy Miller were in the Senate as the senior member of his party from Virginia."

A Miller spokesman later said Miller has "absolutely no agreement or understanding of any sort" that would lead to the appointment of any of his supporters to a federal judgeship. Miller afvocates use of independent review panels to recommend condidates for such positions, the spokesman said.

Miller and Howell have had frequent, pronounced disagreements fro more than a decade. Last week Miller's staff disclosed that Howell was being asked not to take a formal role in the Miller campaign.

Miller officials have said they believe Howell, a three-time candidate for governor, is too controversial a figure and would detract from the issues in the Senate race.

But here in the conservative Richmond area, where Howell is especially unpopular, Warner never mentioned the disagreements between Howell and Miller. Instead, he criticized Miller for saying this weekend that Howell would be helpful in uniting the Democratic Party behind his campaign.

"However much Andy Miller wants to present his record as that of a conservative, it is the record of a liberal - and he's attempting to pull the wool over the eyes of Virginia's voters," Warner said.

Warner's remarks, in a speech to the Richmond Rotary Club, reflect an escalated effort in the Warner camp to tie Miller to Howell, despite Miller's long record on behalf of the moderate faction of the state Democratic Party.

In 1973, for example, when Howell was running as an independent candidate for governor, Miller refused to support him and announced instead he would write in the name of John Warren Cooke, the conservative speaker of the Virginia House of Delegates.

"Andy is trying to embrace (conservative Sen.) Harry Bryd with his right arm while he has his left around Howell." Warner said yesterday. "That's beyond belief. Nobody's arms are long enough to reach that far."