South Korea's top baseball league reverted to a tighter reserve clause on foreign players on Tuesday.

Presently, if foreign players in the Korea Baseball Organization (KBO) don't re-sign with their original teams after their contracts expire, the teams retain the rights to such players for two years. Presidents from the 10 clubs decided to increase the period back to five years at their board meeting.

The period had been lowered from five years to two years in January 2014.

The KBO said the change will take effect after the ongoing season and will not apply retroactively.

If the KBO teams don't make an offer to re-sign foreign players, then such players become free agents, able to sign with any club in South Korea or elsewhere. In cases in which the teams make such an offer and players choose not to accept it, the teams have a choice of retaining the players' rights or giving them their unconditional release.

Last winter, several teams released their unsigned foreign players outright, which allowed them to join other clubs in the KBO. In the past, clubs had been reluctant to grant foreign players their unconditional release because they didn't want their ex-players to compete for rivals and hurt them in the future. (Yonhap)