At least three anti-Henry Howell letters have been mailed to thousands of Virginians recently, including a letter over Rep. J. Kenneth Robinson's (R-Va.) signature that inaccurately accuses Howell of having "urged that Virginia school children be bused into D.C"

The Robinson letter, under a congressional letterhead, has caused the biggest reaction from supporters of Howell, the Virginia democratic guberntorial nominee. The letter was mailed to between 10,000 and 15,000 Virginians by a group that includes a man, Roger Store, who was named by the Senate Watergate committee as a political spy for the 1972 campaign to re-elect President Richard M. Nixon.

The group is called Independent Virginians for Responsible Government, and was formed for the sole purpose of producing an anti-Howell media campaign, according to its chairman, John T. Dolan. Dolan heads the National Conservative Political Action Committee, which has its headquarters in Arlington.

A Robinson aide confirmed yesterday that the congressman authorized sending the letter over his name.

Dolan said all members of the group, including Stone, treasurer David Keene, who ran Ronald Reagan's southern campaign and used to head the coservative Young Americans for Freedom are Virginia voters.

Srone was cited in testimony given to the Senate committee as having assigned people to infiltrate Democratic presidential campaigns. According to testimony, Stone also was given money in 1972 to contribute to Rep. Pete McCloskey's presidential campaign in the name of the Trotskyist Young Socialist Alliance, and then wrote a letter to the Manchester (N.H.) Union-Leader accompanied by a receipt for the contribution from the McCloskey campaign.

Stone later told reporters. "I did some things that were pretty asinine." Other members of the Independent Virginains group include M. Patton Echols, who ran for state attorney general with Gov. Mills E. Godwin in 1973, and former Del. George Mason Green Jr., a conservaive from Arlington.

The Robinsonletter, addressed to "Dear Fellow Virginian," says: "This committee . . . will put hard-hitting TV ads on the air . . . exposing Howell's radical positions on issues like right-to-work, gun-control, unionization of our policemen, firemen and teachers. Not to mention Howell's brief on budget busting deficit spending for Virginia." Dolan said the last sentence contained a typographical error and should have read ". . . his belief in deficit spending."

He also admitted that the first claim in the letter - that Howell "on a Washington-based TV talk show urged that Virginia school children be bused into D.C." - is technically inaccurate. Howell's remarks on the talk show have been in dispute since they became a campaign issue in his 1973 gubernatiorial race against Godwin, but he did refer to the possibility of D.C. children being bused into Virginia rather than the other way around.

According to transcripts and news accounts of the show, Howell said that "some arrangement" short of court-ordered school consolidation could be found to reduct the racial imbalance between the city's schools and those in Virginia suburbs. He made no specific suggestions.

"We can't afford to let the District of Columbia go to pot," he said. "If there's going to some distribution of the young people of the District of Columbia into Maryland and Virginia to save our nation from being a divided black-white nation, then we've got to try this."

The issue came to haunt Howell in 1973, when busing was a volatile issue, although it has not been so far in this campaign. Godwin often repeated th charge that Howell claimed later that a "Today show report the morning of the election that he favored busing caused his narrow loss to Godwin.

Howell said Thursday that the Robinson mail campaign was a "fear tactic" because it is "silent and surreptious."

He said, "I've never urged busing people any place . . . This is designed to evoke emotions and set blacks against whites and undo everything we've achieved in Virginia."

Howell's opponent, Republican John N. Dalton, said yesterday his campaign had nothing to do with the letter and that since he hadn't read if he couldn't comment on it. Dalton said that he had seen a wire service story about the letter. "Some people may consider it strong," he said.

The Independent Virginians group is an independent committee unauthorized by the Dalton campaign, but registered with the State Board of elections.

The Naional Rifle Association has also mounted an anti-Howell, por-Dalton campaign. The anit-gun control lobby's political action arm sent 30,000 letters to its members in Virginia last week, asking them to support dalton and contribute money to the NRA and to another independent group called Sportsmen GO for Dalton.

Dalton himself sent out a two page fund-raising appeal that is largely an anti-Howell letter.

Dalton recently announced his withdrawl from scheduled joint appearances with Howell because of what he called Howell's personal attacks on him and his family. Howell charged there were "rumors" that Dalton had "feathered his nest" while he was a legislator by introducing a bill to increase the service charge a bank could levy for certain small loans. Dalton said the bill applied to state and not national banks such as the one he and his family own stock in: Howell has maintained the bill could apply to national banks.

The Republican lieutenant gubernatorial candidate. A. Joe Canada, has sent out a three-page fund-raising appeal that is devoted to attacks on his opponent. Democrat Charles S. (Chuck) Robb. The letter talks about the "dangerous situation that exists in our home state of Virginia, and links Robb's name with "Out of State Liberal and Big Labor money" and "Out of state liberals" like Averill (sic) Harriman and Abe Fortas.