John Kloch, Alexandria commonwealth's attorney, has released copies of his 1980 and 1979 federal income tax returns as a prelude to seeking reelection this fall.

The returns, which show his 1980 and 1979 income consisted almost entirely of his salary as commonwealth's attorney, are being made public, Kloch said, because he believes in complete financial disclosure by public officials, even though not required by Virginia law.

Neither Kloch, a Democrat, nor any other candidates have formally announced their candidacy for the four-year term as prosecutor.

The final date for party candidates to file for the primary Sept. 8 is August 7. The primary, traditionally held in June, was delayed this year because of redistricting required by the 1980 census. The primary also will include contests for sheriff and for the House of Delegates.

The general election, set for Nov. 3, will include contests for governor, lieutenant governor and attorney general, as well as statehouse and local offices. No primaries will be held for the statewide offices since party candidates are to be nominated at state party conventions set for late this month and early next month.

In his 1979 federal tax return, Kloch reported an adjusted gross income of $41,036.43, and in 1980 reported $48,477.48, reflecting salary increases approved by the legislature for state prosecutors and additional increases approved by the Alexandria City Council. As of February of this year, the post pays $54,351 a year.

Kloch said he and his wife Donna own only one piece of real estate, their house at 2800 Ridge Road Dr., Alexandria, valued at about $115,000.

Virginia law requires most city and county officials, but not commonwealth's attorneys, disclose their property holdings and interest in corporations, but does not require disclosure of income tax information, Kloch said last week. Kloch also made public his income tax returns two years ago, when he was elected to the prosecutor's office in a special election.

That election was set after a city bingo scandal resulted in the resignation of former commonwealth's attorney William L. Cowhig, who was tried and acquitted on bribery and gambling charges. Cowhig resigned rather than face trial on a third, bingo-related charge and last December was disbarred by the Virginia State Bar over a separate incident. Cowhig's appeal of the disbarment was rejected by the Virginia Supreme Court last month.

Kloch, who was assistant commonwealth's attorney from 1974 to 1979, disassociated himself from Cowhig and ran for election with a campaign pledge to bring "integrity" to the office.

In a statement released with his tax forms last week, Kloch said, "I believe that one in the sensitive post of chief prosecutor should go beyond the minimum requirements to assure complete confidence in the city's only elected law enforcement professional."