UPDATE 1-Thai king approves $16 bln borrowing bill for COVID-19 response

* New borrowing to add growth by 1.5 ppts in 2021-2022

* Public debt to GDP ratio seen at 58.56% end-Sept (Adds detail, deputy PM, finance minister’s comments)

BANGKOK, May 25 (Reuters) - Thailand’s king has approved a bill to allow borrowing of up to 500 billion baht ($16 billion) to support the country’s response to COVID-19, the Royal Gazette said on Tuesday, as authorities struggle with a third wave of infections.

The Southeast Asian country’s latest, more severe coronavirus outbreak has accounted for about 80% of the country’s total infections and about 90% of its deaths.

The borrowing was less than an earlier plan of 700 billion baht approved by the cabinet earlier this month.

The new borrowing must be done by September 2022. It will go to parliament next month.

Of the total 500 billion baht, 300 billion will be for relief measures, 170 billion for reviving the economy and 30 billion for tackling the outbreak.

“The outbreak should be contained in the second quarter... and the new borrowing should be sufficient,” Deputy Prime Minister Supattanapong Punmeechaow told a briefing.

With the new borrowing and current financial support schemes, the government has 1.25 trillion baht ($39.9 billion) to help the economy versus last year’s 1.9 trillion baht, Supattanapong said.

The government’s earlier 1 trillion baht borrowing is almost used up, officials have said.

The new borrowing will help the economy in 2021 and 2022 expand by a further 1.5 percentage points from a projected base case, Finance minister Arkhom Termpittayapaisith told the briefing, repeating an earlier ministry statement.

“It will help get economic and social systems back to normal quickly,” he said.

Last week, the state planning agency cut its GDP growth forecast to 1.5%-2.5% from 2.5%-3.5% due to the outbreak.

The country’s public debt to GDP ratio would be 58.56% at the end of September, still within its 60% limit, Arkhom said.

The finance ministry plans to borrow up to 100 billion baht of the new borrowing plan by September, Patricia Mongkhonvanit, head of the ministry’s public debt management office, told a separate briefing. ($1 = 31.35 baht) (Reporting by Orathai Sriring, Panarat Thepgumpanat, Satawasin Staporncharnchai and Kitiphong Thaichareon Editing by Martin Petty)