By Byungwook Kim and Heekyong Yang

SEOUL (Reuters) - South Korea's unionised truckers headed back on the roads on Wednesday after the union and the transport ministry reached a tentative late-night agreement, ending a nationwide strike that crippled ports and industrial hubs.

The transport ministry and truckers union agreed on late Tuesday to extend the truckers' minimum freight rates and continue discussing expanding a guarantee of minimum pay for carrying cargo to cover additional products. The transport ministry will also review expanding fuel subsidies.

Shares in some affected industries rose after the eight-day strike had delayed cargo shipments from autos to cement and alcohol, costing South Korea more than $1.2 billion in lost output and unfilled deliveries.

"So the strike has been called off until our demands are passed in parliament," said Park Jung-hoon, an official at the union's Busan chapter, referring to the process the transport ministry must undertake to implement the agreement.

"In the next two to three days, 100% of unionised truckers at Busan port are expected to return to work after they get some rest. There might be some shippers who seek retributions, and in such cases, we will respond strongly."

The strike had been an early test of the new government of President Yoon Suk-yeol and had further stretched global supply chains already disrupted by China's COVID-19 curbs and Russia's invasion of Ukraine.

Woo Sang-ho, the interim leader of the opposition liberal Democratic Party which has a majority in parliament, welcomed the agreement but said the issue of guaranteeing freight rates required legislation and called for "fundamental improvement" to address conditions faced by the truckers.

"The ruling party must not remain a mediator, but should promote directly" the minimum freight rate system as it is directly tied to people's safety, a joint statement with the union and a Democratic Party committee said on Wednesday.

There was confusion about whether the government and Yoon's ruling conservatives agreed to make the minimum pay system a permanent feature or merely extend a temporary measure for another fixed period, union official Kim Jae-gwang said.

Business lobby group Korea International Trade Association said the minimum freight rate system "does not take into account market functions", reduces production and weakens international competitiveness by "placing a one-sided burden on the shipper".

SHARES GAIN, PRODUCTION RESUMES