A major boost in the number of wheelchair-accessible taxis will follow a planned expansion of the city’s fleet of “green” taxis.

Under an agreement between Mayor Bloomberg, the City Council, and state lawmakers, the council today will approve an amended bill that provides for the sale of 254 medallions for alternative-fuel cabs in an auction next month, and the state Legislature will put on the fast track a measure to sell a minimum of 150 additional medallions within months, all of which will be earmarked for wheelchair-accessible vehicles.

The agreement averts a confrontation between the council and the Bloomberg administration, which as recently as last week had opposed a council proposal to mandate additional medallions for both environmentally friendly and wheelchair-accessible cabs. Next month’s auction was to have been the city’s last scheduled medallion sale.

The chairman of the Taxi and Limousine Commission, Matthew Daus, had told lawmakers at a hearing that the current slate of wheelchair accessible cabs was marred by technical glitches, and criticized the bill for seeking to change the auction rules at the last minute. Two days later, Mr. Bloomberg announced plans to nearly quadruple the number of “green” cabs at the auction but offered no increase for wheelchair-accessible cars.

With the council planning to pass its own bill to secure the wheelchair-accessible medallions, officials turned to Assemblyman Vito Lopez, a Democrat of Brooklyn, and Senator Frank Padavan, a Republican of Queens, to sponsor bipartisan legislation authorizing a second medallion sale.

“While we support the mayor’s call to make our city more environmentally-friendly, it’s also important that taxi cabs are accessible to as many New Yorkers as possible,” the council speaker, Christine Quinn, said in a statement.

The campaign coordinator for the Disabled Riders Coalition, Michael Harris, said he is happy a deal has been reached but expressed disappointment that the new wheelchair-accessible medallions would be delayed beyond next month’s auction. “Is it perfect? No,” Mr. Harris said. “But we believe it’s a step in the right direction and moves us closer to a fully accessible taxi fleet.”

Under the plan, the number of “green” cabs will increase to 273 from 19, and the number of wheelchair-accessible vehicles will go to 231 from 27.

The practical impact of the added accessible cabs will be limited. Because yellow cabs cannot be reserved in advance, and with about 13,000 taxis on the streets, disabled riders have a statistically minimal chance of hailing one tailored for their needs.

Despite the long odds, the agreement is a victory for disabled riders, the chairman of the council’s Transportation Committee and a sponsor of the original bill, John Liu, said. The additions, he said, would give the city enough of a sample to study the feasibility of converting the entire taxi fleet to wheelchair-accessible cabs.