Rezoning to permit development of a major industrial park - the largest in Loudon County and one of the largest in Northern Virginia - was unanimously approved yesterday by the Loudon County Board of Supervisors.

The project, called Leegate Industrial Park, could provide 3,000 additional jobs to the county if the 380-acre site east of Leesburg Rte. 7 is developed as envisioned over eight years with both heavy and light industry and a hotel and convention center.

The supervisors also approved zoning for a $5 million satellite communications center planned by Satellite Business Systems.

Yesterday's rezonings were hailed by County Planning Director John Dugan as signalling a new wave of "managed growth" that will further the achievement of a balance between commercial and residential needs.

But Carl F. Henrickson, chairman of the Board of Supervisors, sounded a cautious note.

"we've had a number of these things before the board with grandiose schemes and nothing ever developed," Henrickson said. He cited a proposed industrial park approved by the board in 1970 that was to have been located at the western edge of Dulles International Airport but which failed to take shape.

Referring to the Leegate Industrial Park developer, North American Doctors Investment Fund, Henrickson said, "I wish them Godspeed. If these people can put it together it will go a long way to changing the complexion of Loudoun County from a bedroom community for Washington to a place where people live and work."

The leegate project, two miles east of Leesburg south of Rte, 7, could add $125 million to the county's tax base.

County Administrator Philip A. Bolen said the developer has "some firm commitments from users, but we don't know who they are at this point."

But Board member Frank Raflo said he doesn't believe the developers have any signed commitments.

The town of Leesburg has agreed to extend its sewer and water lines to serve the site, one of the first such extensions in recent years, according to planning director Dugan. He said the developers have agreed to give the county a portion of their property for public services such as a fire station.

The satellite communication facility would be located on Rte. 7, about five miles east of Rte. 28 and would employ about 40 persons, according to Raflo.