Dai-Ichi Kangyo Bank Ltd. of Tokyo has surpassed Citicorp of New York as the world's biggest banking concern as measured by total assets, the banking-industry newspaper American Banker reported yesterday.

As of March 31, Dai-Ichi had dollar-denominated assets of about $207.2 billion, compared with $175.9 billion for Citicorp.

Aiding Dai-Ichi's rise to the top was the sharp appreciation of the Japanese yen against the dollar during the past year, which added $49 billion to the dollar-value of Dai-Ichi's assets. Because the survey converts the assets of Japanese banks into dollars, a rise in the yen against the dollar increases the level of dollar-denominated assets.

Before March 31, Citicorp had held the top spot in the American Banker survey of the world's 500 biggest banks for the past four years. The next three banks in the survey were Japanese: No. 3, Fuji Bank Ltd. of Tokyo with Sept. 30 assets of $143 billion; No. 4, Sumitomo Bank Ltd. of Osaka with $136 billion; and No. 5, Mitsubishi Bank Ltd. of Tokyo with $133 billion. Utility Trade Associations

Face Audit Regulators yesterday said they would audit tens of millions of dollars of expenditures made by utility trade associations based in Washington to see if the activities actually benefit customers.

Customers fund these associations through rates charged by local utilities that are members of the advocacy groups.

The National Association of Regulatory Utility Commissioners said associations that will be audited are the U.S. Committee for Energy Awareness, a nuclear-power advocacy group, the United States Telephone Association, representing more than 1,100 telephone companies, and the American Gas Association, representing all major gas-distribution and pipeline companies.

NARUC previously audited the Edison Electric Institute, an electric-utility association. The controversial audit resulted in a report outlining which portions of membership dues state commissions could disallow utilities to pass through to customers in rate hikes. USTA and the U.S. Committee for Energy Awareness had no comment late yesterday. The AGA could not be reached. Tandy Introduces Low-Priced PC

Tandy Corp. yesterday announced that it has revamped its line of personal computers with five new machines, including one that it said is cheaper and four times faster than IBM's best-selling XT.

The new computers combine plentiful features with low prices and should put pressure on International Business Machines Corp. and other makers of PC-compatible computers, analysts said.

Analysts were most impressed by the $1,699 price tag on the new Tandy 3000 HL, which is intended to compete with IBM's XT, the world's best-selling personal computer. U.S. Optimistic on Semiconductor Talks

U.S. and Japanese officials continued negotiating through last night in an effort to reach agreement on a knotty semiconductor trade issue before a midnight deadline.

Industry and government sources appeared optimistic that an agreement could be reached that will more than double U.S. semiconductor sales in Japan and end the Japanese practice of dumping chips in the United States at below fair-market value. An announcement is expected as early as this morning.