As part of an effort to halt the illegal flow of handguns from Virginia to Washington, federal firearms agents yesterday seized documents from 23 Virginia gun dealers who allegedly made 170 illegal gun sales to federal agents in the last three months, the U.S. Bureau of Alcohol, Tobacco and Firearms reported.

The records will be presented as evidence against the dealers before federal grand juries, ATF spokesman Fred Murrell said.

An 18-month ATF study of handguns used in Washington area crimes revealed that Virginia was the single largest source of the firearms, accounting for 2,000 or 27 per cent of the handguns investigated, Murrell said.

Maryland was the second largest source. The District has a strict guncontrol law that limits gun sales to police and security personnel only.

Over the last three months 76 Virginia dealers who had previously sold guns that eventually were used in crimes in Washington were approached by federal agents carrying out-of-state indentification to purchase a gun, according to Murrell. It is illegal to sell a gun to a nonresident of the state where the purchase is made.

In 23 of the 76 gunshops the dealers suggested that a third party with a valid Virginia driver's license fill out the required federal forms, Murrell said. The ATF agent then called a colleague with a Virginia license to perform what Murrell called the "straw purchase."

Agents made at least three separate purchases in each of the 23 shops targeted yesterday, Murrell said. Ninety per cent of the 170 weapons bought were handguns, he said.

The 23 dealers are located in Bristol, Danville, Richmond, Norfolk and Roanoke, Murrell said. The maximum penalty for the illegal sale of a gun is five years imprisonment and a $5,000 fine.