A Democrat senator is expected on Monday to ask the Securities and Exchange Commission to review the stock market's structures, Dow Jones Newswires reported, reviving a debate over the market impact of computer-based trading.

Ted Kaufman, a long-time advisor to Vice President Joe Biden, said regulatory moves in the past decade have had the unintended consequence of making the stock market too fragmented, according to a letter to be sent to SEC Chairman Mary Schapiro that was reviewed by the news agency.

There are now potential conflicts of interest on Wall Street trading desks trying to serve both retail clients and high-frequency trading firms, the Delaware senator said.

In response, the regulator should undertake a 'zero-based review' of the market, the letter was quoted as saying. Zero-based reviews examine all parts of a structure.

Kaufman and the SEC could not immediately be reached for comment by Reuters outside regular U.S. business hours.

(Reporting by S. John Tilak in Bangalore; editing by John Stonestreet)