An effort to exempt Fairfax County from a controversial and complex annexation bill was defeated in Virginia Senate committee today. The bill would force counties to pay cities to prevent them from annexing county territory.

The Fairfax Senate delegates had attempted to amend the bill to allow Fairfax two years to study the annexation bill and decide how best to prevent what it predicts will be the "balkanization" of the 399-square-mile county. But the amendment, which would have exempted the county from annexation actions during the study period, was defeated on a 9-to-6 vote.

The bill's patron, Del. Thomas J. Michie (D-Charlottesville), supported the Fairfax exemption because in return the Fairfax senators said they would vote for his bill. Without their five votes the bill may be in jeopardy, although Michie and Sen. Joseph V. Gartlan remained optimistic that the amendment would be resubmitted and approved later this week.

"Without the amendment, our five votes will go against the bill," Gartlan said, "This is probably a ploy by the bill's opponents to get it defeated with our votes."

The bill, which passed the House early this month, is so complicated that even legislators who voted for it said they didn't understand all of it.

The bill inspired the entire nine-member Fairfax County Board of Supervisors to make an unusual mass visit to the General Assembly last Monday, during which they protested angrily that the bill would have a disastrous effect on the county. An attorney who came with them estimated the county would have to pay about $333,000 the first year and $500,000 the next to Alexandria if the bill was approved.

The bill would end a moratorium on annexations that has been extended annually for at least six years while a committee attempted to work out a solution to the problem. In Virginia, before the moratorium, cities were allowed to enlarge their size and thus their tax base through annexation if they could prove they provided better service than the county.

The current proposal would allow urban counties such as Fairfax to gain immunity from such annexations by paying into a special fund. Money from this fund would be funneled into the city to compensate for revenues it might otherwise be able to get through annexation.

Not unexpectedly, this proposal has met with vehement opposition from some of the urban counties that might have to pay, and from the cities that do not want counties to be able to buy immunity.

Sen. Edward E. Willey (D-Richmond) for example, senior member of the Senate and leader of its conservative faction, opposes the bill because Richmond wants to be able to annex more land from suburbia. He has been seen energetically buttonholing fellow legislators since Monday in an effort to get them to vote against the bill.

Earlier, Sen. Willey, in an extraordinary Senate floor speech, denied that he had been improperly pressuring other senators to vote against the annexation bill. Although Willey was serious as he spoke, many senators broke into smiles as he described his efforts a "just pleading for a little kindness.

"I have never exchanged a vote for anything," he maintained at one point. But he did concede he had pointed out to other senators measures for their region he had supported and telling them, "I hope you believe in reciprocity.

"One thing I am is frank and blunt," he said. "I don't go around talking behind a senator's back. I say what I say to somebody's face."

Willey said "one of my closest friends" had complained to him about his lobbying tactics on the bill, but he refused later to name the senator.

Earlier the Senate approved, 36 to 0, a House bill that would direct hospitals in the state to give out "family planning information" to the parents of infants born at the hospital.