At least 18 people have been killed and 19 injured as South Korea’s wildfires continue to ravage the country’s southeast, according to the latest numbers from the Ministry of the Interior and Safety.

The “unprecedented” crisis remains critical, according to acting president Han Duck-soo, who said the fires are “rewriting the record books for the worst wildfires in our nation’s history”.

More than 23,000 people have been evacuated and several heritage cultural sites affected, including a 1,300-year-old Buddhist temple that was destroyed.

A firefighting helicopter crashed in the mountains of Uiseong county just after midday on Wednesday, according to authorities, who are investigating the cause.

Thousands of firefighters and about 5,000 military personnel have been deployed to contain multiple blazes, as well as helicopters from the US military stationed in Korea.

On Tuesday, the national fire agency said it had raised the crisis to the highest fire response level, the first time this year such an alert has been issued.

Wildfires are relatively uncommon in South Korea, and related fatalities are rare. The current fires, which have killed 18 people within the past few days, are already the deadliest in the country’s history.

About 17,000 hectares of forest have also been destroyed, making the fires the third largest in South Korea’s history in terms of area.

The blazes raging in the city of Uiseong burned down the Gounsa Temple, built in 618 AD, which was one of the largest temples in the province.

A Buddhist architectural structure deemed a national treasure from the Joseon Dynasty (1392-1910) was also destroyed, forestry authorities confirmed.

Acting president Han said all available personnel and equipment have been deployed, but strong winds continue to hamper the support efforts.

“We were desperately hoping for rain today or tomorrow to help extinguish the flames,” Han added.

“This level of wildfire damage is unlike anything we’ve experienced before.”

There was no rain forecast for the region on Wednesday and only a small amount – five to 10mm – expected on Thursday, according to the Korea Meteorological Administration.

Han said the government will thoroughly review all shortcomings in the wildfire response once the crisis is controlled and seek to improve prevention strategies for the future.

“Once a wildfire starts, extinguishing it requires tremendous resources and puts precious lives in danger,” he said.

South Korea has been experiencing drier than normal conditions with less rainfall than average. There have already been 244 wildfires this year – 2.4 times more than the same period last year.

The government also promised to strengthen enforcement against illegal burning -one of the main causes of wildfires – and crack down on individual carelessness.

The wildfires first broke out last Friday in Sancheong County, in the country’s southeast, but have now spread to neighbouring cities of Uiseong, Andong, Cheongsong, Yeongyang and Yeongdeok.