A credit card affiliate of Korea Exchange Bank (KEB) reported to government authorities Monday it had barred the entry of union workers at the company's Seoul main office starting from Sunday evening in a bid to head off a possible crippling strike by the unionists.

Korea Exchange Bank Credit Service (KEBCS) said it surrounded its main office with some 200 security personnel and have placed replacement workers at the firm's main computer room.

The credit card firm also warned union workers to return to their posts by Saturday or face dismissals. The firm said it had already notified some 40 percent of a total 662 employes that they could be dismissed upon failing to report back to work at the weekend.

For those choosing to resign, the company said it would offer 12 months' wages as compensation and additional sums to help stabilize the livelihoods of former employees.

Some 19 individuals have applied for the packages so far, the firm said.

Some 500 union workers staged rallies in front of company headquarters Monday to protest the company's surprise move, demanding that management withdraw its union ban, provide employment guarantees and scrap its plans for restructuring and planned mergers.