Updated

The European Parliament has backed a rescue plan for the world's biggest cap-and-trade system for emissions of carbon dioxide, the most prevalent greenhouse gas.

In a 344-311 vote, European lawmakers in Strasbourg, France, approved Wednesday a proposal to delay an auction of allowances in the EU's emissions trading scheme.

The delay was designed to boost the carbon price, which has dropped below 5 euros ($6.5) per ton due to an oversupply of allowances and Europe's economic slowdown.

Introduced in 2005 as a tool against climate change, the system allows power plants and big factories to trade CO2 permits, providing an incentive to cut emissions.

The plan passed Wednesday was an amended version of a proposal rejected by the European Parliament in April. It must also be approved by EU governments.