General Motors Korea cancelled a news conference on Monday after a dozen temporary workers forced their way into the event venue minutes before, chanting slogans that called on the automaker to hire them full time.

GM had issued a press statement about its plans for the restructured, slimmed-down unit.

Reuters said the news conference was to be the first since GM Korea averted bankruptcy last month after winning major concessions from its union of regular workers as well as government funding, and was to be attended by the heads of both GM Korea and GM International.

But the cancellation illustrated how the status of temporary workers, seeking job security at a time of uncertainty at the automaker, remained a challenge for GM Korea in a country where auto unions are known to be strong and militant.

According to the news agency, about 15 minutes before the news conference was scheduled to begin at 10am local time, temporary workers entered the venue holding signs and chanting slogans such as, 'Abolish non-regular positions' and 'Let's fight until the end and return to the factory'.

Hwang Ho-in, head of the union of temporary workers at GM Korea's main factory compound in Bupyeong, said upon entering the venue that he and his colleagues would not interfere with the event and that they were present just to watch proceedings.

"Management thinks we are a terrorist group, a violent group or something like that," Hwang told reporters, after the event was cancelled. The president of GM International, Barry Engle, and GM Korea chief executive Kaher Kazem did not make their planned appearances.

"We are placing top priority on the safety of our employees," GM Korea spokesman Park Hae-ho told Reuters.

The news agency noted that, last month, full time workers entered Kazem's office and destroyed furniture after the automaker said it was unable to make planned bonus payments because of a shortage of cash.

GM subsequently asked employees overseas to refrain from visiting its South Korean sites until further notice due to security concerns.

A South Korean court has said GM Korea should recognise temporary workers as full-time employees, in a ruling the automaker has since appealed. On the same day, GM announced the planned closure of one of its four South Korean factories.

GM Korea has some 2,000 temporary workers. They fear more restructuring and job cuts even after the rescue deal as plants struggle with low utilisation rates, Hwang told Reuters.