Slovak lawmakers on Wednesday imposed an 80 percent tax on revenue from the sale of carbon dioxide (CO2) emission permits for the next two years in a bid to patch a hole in the state budget.

The tax will apply to 133 of the 144 Slovak companies for which the previous leftist government had earmarked more emission permits in 2008-2012 than they needed, Finance Minister Ivan Miklos said.

The European Union allocates CO2 emission credits to individual countries which then hand them out to companies for free.

Companies that emit more carbon dioxide than the credits cover must buy further permits from others who emit less.

According to a finance ministry analysis, 133 companies received 40 percent more emission permits than they needed over the past two years and could have sold them for approximately 318 million euros (417 million dollars).

Unused permits for 2008-2012 are worth a total 666 million euros, Miklos said.

Slovakia's austerity-minded centre-right government, in power since July, could raise up to 150 million euros from the tax in 2011-2012, according to the finance ministry.