The Virginia Electric and Power Co. needs $11 million more in annual revenues on top of its pending $246 million rate increase request company officials announced yesterday as a major courtroom battle on the request opened here.

But the company will not seek the $11 million at this time. "It's an update," said John Riley, a private attorney hired by Vepco for the case. "It shows we need $257 million but we're still asking for $246 million."

The disclosure came in a hearing on the rate increase request before the State Corporation Commission as Attorney General J. Marshall Coleman and a score of lawyers representing everyone from big business to low-income consumers attacked the company for alleged inefficiency and demanded a reduction in the rate request.

The request, which would raise electricity bills by more than 20 percent for 1.2 million Vepco customers, is the largest pending anywhere in the nation.

"The company's request is greatly overstated and can be substantially cut without impairing the company's ability to provide service," said Coleman, whose office represents consumers in utility cases.

Coleman suggested that "monetary pressure" be brought to bear on Vepco management by cutting the rate of return the utility is allowed to pay its investors from the current 9.6 percent to 9.4 percent until management begins running the company more efficiently.

Under a day of grueling cross-examination on the witness stand, Vepco president Stanley Ragone warned that such methods would threaten the company's ability to attract capital and would slow its $600-million-a-year plant construction program, thus possibly resulting in "severe capacity shortages in 1982 . . ."

The highly detailed but nevertheless dramatic confrontation in the commission's imposing courtroom here yesterday followed three days of public hearings across the state. The intense activity signals a rising concern with skyrocketing utility rates.

The commission staff, a body of experts that operates largely independently of the three decision-making commissioners, submitted testimony that Vepco could get along with a $170 million increase.

Testimony submitted in the case of James R. Wittine, the commission's director of energy regulation, reports that from 1967 through 1977 the price that Vepco customers paid for a kilowatt hour of electricity "has out-paced the increases in the consumer price index and has more than doubled."

The cost of electric service in Virginia is high in comparison with costs in other states across the country, according to Wittine's testimony.

(Wittine) recommends that the company endeavor to determine if performance of its units can be improved," said commission counsel Richard D. Rogers yesterday. "The results of his study indicates - that relatively small percentage improvements in Vepco's generating performance can be worth millions to the company and thus to its customers."

The largest single component of the rate increase request is due to the opening of Vepco's North Anna nuclear plant. The commission last May gave Vepco temporary permission to raise rates by $82 million, thus charging its customers for the cost building the plant.

The $82 million is part of the overall rate request, and final commission approval on it is still pending.

Perhaps the most controversial part of the request is for ratepayers to begin paying for plants under construction even though they are not currently benefitting from them.

In a related development, Ragone announced yesterday that the FBI has investigated allegations of unspecified "wrongdoing" at Vepco's pump storage plant under construction in Bath County and has found none. A public witness before the commission on Thursday alleged that a worker on the site ordered $30,000 in unneeded bolts from a friend and was fired for doing so.