The United States Environmental Protection Agency proposed approving a vehicle low emission program for the state of Massachusetts, but will postpone acting on those parts of the plan that include the tough zero emission standards adopted in California that Justice Department lawyers oppose, Reuters said.

According to Reuters, Massachusetts wants to incorporate the California vehicle zero emission standards that the Bush administration said earlier this month infringed on the federal government’s authority to set vehicle mileage requirements.

Reuters said The White House sided with vehicle makers DaimlerChrysler and General Motors in opposing the California standards. The Justice Department, acting on behalf of the administration, filed a brief with 9th U.S. Circuit Court of Appeals supporting a federal judge’s injunction that delayed the California vehicle emission standards from taking effect for two years until the 2005 model year, Reuters added.

California recently signed into state law a measure to regulate emissions of carbon dioxide, a greenhouse gas, which vehicle makers contend is a veiled attempt to require stricter fuel economy standards, which only Congress can regulate, Reuters said.

Reuters said that environmentalists have criticised the Bush administration for opposing California’s tough vehicle emissions standards, arguing that the White House wants to protect US vehicle makers at the expense of clean air.

The California standards that Massachusetts wants to adopt would require 10% of vehicles sold to produce no pollution, Reuters said.

Reuters noted that US vehicle makers would have a tougher time in meeting such a stiff requirement compared to Japanese rivals Toyota and Honda which already sell several low emission hybrid vehicles that also have higher fuel economy.