In a further escalation of the battle between the nation's two largest intercity bus companies, Greyhound Lines filed a lawsuit yesterday seeking to block the Interstate Commerce Commission's ruling on Thursday that temporarily increases competition on intercity bus routes.

The appeal, filed in the Fourth U.S. Circuit Court of Appeals in Richmond, seeks to overturn the ICC's ruling on the grounds that the agency overstepped its authority, a Greyhound spokesman said. Greyhound, whose president called the ICC's ruling "irresponsible and fuel-wasteful," was joined in the suit by eight independent bus companies and two independent bus associations, according to lawyers for Greyhound, the largest bus firm.

Greyhound also filed a petition with the commission requesting a stay of its decision pending the appeal filed in Richmond. Next week Greyhound will file with the appeals court a request for a stay of the ruling and an expedited hearing on the stay.

The ICC decision, hailed by Trailways Inc., Greyhound's nearest competitor, gives permission for all interstate bus companies to serve additional communities without specific permission from the government. The ICC's action was intended to make more service available to intercity bus riders and consequently save fuel.

Trailways basically sought the ruling, in the tradition of its aggressive President J. Kevin Murphy, to open up competition on routes now dominated by Greyhound.

Greyhound now dominates 63 percent of the industry, Murphy said in a telephone interview, and Trailways "is just a smaller carrier trying to compete in the market. Greyhound has done everything it could to stop us . . . They're trying to keep total monopoly control."

Greyhound President Frank L. Nageotte called the move by Trailways to receive the favorable decision, "a self-serving ploy to divert passengers from Greyhound by exploiting the gasoline shortage and by misrepresenting the bus industry's capacity to handle more passengers."

Trailways representatives had told the ICC that the opening up of routes is necessary because more people want to ride buses because of the gasoline shortage and fuel is being wasted because Trailways is prohibited from picking up passengers in certain cities served by Greyhound.