Prosecutors said Monday they will seek arrest warrants for 10 unionized rail workers for refusing to respond to a summons as part of an investigation into an ongoing strike.

More than 6,500 unionized workers of state-run Korea Railroad Corp. (KORAIL) went on strike last Monday in protest against a government decision to set up a new rail operator that they claim is the first step toward privatization.

"Arrest warrants will be sought for 10 union members, including a union leader, as they have refused to appear for questioning," a prosecutor close to the investigation said.

The summons came after KORAIL filed a charge against 190 union members for instigating the "illegal walkout," saying that their action caused huge financial losses.

The Supreme Prosecutors' office said it will apply for arrest warrants with district courts within the day and bring in the union members for questioning.

KORAIL workers have criticized the planned establishment of the affiliate, claiming that it is the first step toward privatizing the state-run company, which they say could result in mass layoffs and fare hikes.

The company has denied the claim, saying the new unit will be 41 percent and 59 percent owned by KORAIL and state-run investors, respectively, and that private firms will never be allowed to buy stakes in it.

The new service will run from Suseo-dong in southern Seoul to the southern provincial city of Busan. After several delays, it is expected to begin operations in 2016.

So far, a total of 7,608 striking workers have been removed from their positions for their participation in the walkout and will likely face disciplinary action, KORAIL said.

Subway services in Seoul and its surrounding Gyeonggi Province were partially affected Monday after Seoul Metro, a public corporation that runs Seoul subway lines one through four, launched a joint strike with KORAIL, it said.

The number of trains on Subway line No. 3 were brought down by an average of around 13 percent, it said, adding that other lines were operating at the normal level.

Daily KTX services will also be reduced by 10-12 percent starting from Tuesday and the operation of the normal-speed Mugunghwa trains will also be affected, it added. (Yonhap news)