The revised plan will give airlines up to three years to repay loans guaranteed by the government, an increase from two years originally, the Industry Ministry and the Ministry of Transportation said in a joint statement.
"The crisis among airlines is more long-lasting and serious than expected and it is necessary to give further assistance to the industry," the ministries said.
Norwegian Air, which last week sought court-administered bankruptcy protection as the carrier seeks to stave off collapse, has already received a maximum 3 billion crowns ($333.7 million) allotment under the plan.
The government on Nov. 9 rejected Norwegian's plea for an additional injection of cash.
Nordic carrier SAS, which has not yet sought loan guarantees under Norway's plan, can apply at any time before June 30 next year, the government said. The original deadline was end-2020.
The maximum allotment available to SAS under the guarantee programme is 1.5 billion Norwegian crowns.
($1 = 8.9914 Norwegian crowns)
(Reporting by Terje Solsvik; editing by Victoria Klesty and Barbara Lewis)