MELBOURNE, June 23 (Reuters) - Australia's parliament has...

MELBOURNE, June 23 (Reuters) - Australia's parliament has approved plans to pay Viva Energy Ltd (VEA) and Ampol Ltd (ALD) up to A$2.3 billion ($1.8 billion) to keep their struggling oil refineries open to protect the country's fuel security, Energy Minister Angus Taylor said on Wednesday.

Under the plan announced in May the government agreed to top up earnings at Australia's two remaining refineries when refining margins are weak through 2027, with an option to extend to 2030.

It also agreed to provide up to A$125 million each to Ampol and Viva to upgrade their refineries to produce ultra-low sulphur petrol by end-2024.

Payments to the refineries will begin from July 1, the government said.

The fuel industry will also be required to hold minimum stocks of 24 days of petrol and jet demand and 20 days of diesel demand from July 2022, with a 40% increase in diesel holdings required from July 2024.

Australia's ageing refineries have found it difficult to compete with much bigger, new refineries across Asia. The country's two other refiners -- BP BP.L and Exxon Mobil Corp XOM.N -- are shutting their plants this year.