Neeraj Kumar said the players under scrutiny were all Indians from one team but declined to name them.
Three cricketers, including Indian fast bowler S Sreesanth, were arrested last week over allegations of spot-fixing.
Sreesanth and the families of the other two have denied the charge.
The arrested players - Sreesanth, Ajit Chandila and Ankeet Chavan - all belong to the Rajasthan Royals team. On Tuesday, a court extended their custody for five more days.
The players have also been suspended by India's cricket board and the Rajasthan Royals.
Spot-fixing involves illegally rigging parts of a match, for example by timing the delivery of a deliberate wide or no-ball, to benefit bookmakers or those betting on matches.
"The contours of our probe are likely to widen soon and we are hoping to crack a fresh syndicate of bookies," the Delhi police chief told The Indian Express newspaper.
"We are looking at other teams and other players as well, and specifically at three Indian players from one team," the paper quoted Mr Kumar as saying.
The police chief declined to name the players saying it will "affect our investigation".
Police say players use codes like "rotating their watches", "putting towels in their pants", "taking out lockets from their shirts", or "making signs with their clothes" to communicate with the bookmakers.
The arrests of Sreesanth, Chandila and Chavan have shocked Indians who are fanatic about cricket.
More than a dozen bookmakers have also been arrested in connection with the spot-fixing inquiry.
On Tuesday, Mumbai police arrested actor Vindoo Randhawa, the first Bollywood personality to be arrested in connection with the scandal. Mr Randhawa, who won series three of Bigg Boss - India's version of the television show Big Brother - has made no public comment yet.
The sixth season of the IPL, which is considered to be the world's showcase for Twenty20 cricket, is currently under way in India.
Top Indian and international players are taking part, contributing to what is the world's richest cricket tournament.
The Delhi police chief has said they are watching at least three more cricketers for their role in alleged spot-fixing in the Indian Premier League (IPL), media reports say.