Rep. Dan Daniel, the dean of Virginia's delegation in the U.S. House of Representatives who is currently under investigation by the House ethics committee for claiming possibly improper travel expenses, announced yesterday that he would seek a 10th term.

Daniel, a conservative Democrat who had been expected to seek reelection, made the formal announcement in his home-town newspaper, The Danville Register. The 71-year-old legislator, who is a senior member of the House Armed Services Committee, was not available for comment yesterday.

"I am guilty of what some consider political sins," he told the newspaper. "And, I have explained this to my constituents on numerous occasions. These particular transgressions are flying and playing golf.

"I have said from the outset that I would fly with anyone who was a qualified pilot, and play golf with anyone who would pay my greens fees. The investigation presently under way is plowing old ground, as far as the residents of the 5th District are concerned."

Daniel is being investigated for accepting 23 free airplane rides provided by Beech Aircraft Corp., a defense contractor, while urging Congress to direct the Pentagon to buy 24 Beech C12 airplanes for the military.

Recently, the ethics committee broadened the scope of its investigation to include whether Daniel submitted false travel vouchers for car travel to his district when he had flown there for free in the Beech planes.

"I had only heard rumors that he was going to seek reelection," said Robert L. Watson, executive director of the Democratic Party of Virginia. "I think if he had not decided to run, a number of Democrats and Republicans were planning to seek the seat."

Watson said he assumed Daniel's announcement was serious. "Certainly, if Congressman Daniel wishes to seek reelection, that's his right to do that. And if he's the nominee of the party, then the party will back his candidacy."

Possible Democratic candidates mentioned in recent months include J.T. Shropshire, clerk of the State Senate; Robert Crouch, the one-time 5th District party chairman and former Henry County clerk of court, who resigned his job to attend law school at the University of Virginia, and Del. Franklin M. Slayton (D-South Boston).

Slayton, a veteran legislator, said yesterday that Daniel had called him Saturday afternoon to tell him of his reelection plans. "It seems to me it's just very early to be announcing for an election next November," said Slayton, "but I'm sure he has his reasons for doing it."

Daniel, in the Danville newspaper article, noted that he continues to be concerned with the flood of foreign imports that threaten industries vital to his district, including textiles and footwear. He also said he wants to introduce legislation to put the nation's special combat troops under one command.