Jan 20 (Reuters) - Australia's Whitehaven Coal said on Friday it expected profit for the first half of fiscal 2023 to more than quadruple thanks to strong pricing, a day after Australia's most populous state said the coal miner could be forced to reserve up to 10% of supply for domestic markets.

The country's largest independent coal miner said it had achieved an average price of A$527 per tonne for its coal in its second quarter, compared with A$211 per tonne a year earlier.

The company now expects to report first-half earnings before interest, taxation, depreciation and amortisation of about A$2.6 billion ($1.80 billion), from A$0.6 billion.

"Strong ongoing demand for high CV (calorific value) coal, coupled with supply constraints, underpinned high prices, a solid December quarter and an exceptional first half result," chief executive Paul Flynn said.

On Thursday Whitehaven said it had met with state officials of New South Wales about plans to force miners to reserve up to 10% of production for domestic markets. The state is concerned about a supply shortfall later this year.

Whitehaven said then it was still reviewing the implications of the scheme and would update markets in the future.

Thawing diplomatic relations between China and Australia were boosting metallurgical coal prices, Whitehaven said. News that China was

relaxing unofficial bans on Australian coal imports

had sent prices to their highest level since June 2022, it added.

Fellow miner Coronado Global Resources said on Thursday it had received enquiries from Beijing about coal sales.

Whitehaven's strong performance came despite repeated delays from torrential rain and flooding, with the Maules Creek and Tarrawonga open cut mines particularly affected.

Whitehaven and fellow miner Yancoal expect fewer wet delays in the second half as Australia's weather bureau forecasts drier weather. Both miners expect labour constraints will remain a drag.

Managed run-of-mine coal production was 4.8 million tonnes (Mt) for the quarter ended Dec. 30, compared with 3.2 Mt a year ago, Whitehaven said.

The miner remained on track to deliver within the range of overall production, sales and cost guidance for fiscal 2023. (Reporting by Rishav Chatterjee and Archishma Iyer in Bengaluru, Lewis Jackson in Sydney; Editing by Sriraj Kalluvila and Bradley Perrett)