Honda Motor Co. (7267.TO) said Friday it was halting car production for an extra day and other Japanese auto makers said they were unsure when factories would be back online after a major quake ravaged a key parts supplier.

Severe damage to Riken Corp.'s (6462.TO) factory in Kashiwazaki, in north- central Japan near the epicenter of Monday's magnitude 6.8 temblor, has wreaked havoc at Japan's top automakers who rely on the company for key engine and transmission parts.

Riken said Friday it hopes to restart production of some auto parts on Monday. Workers had finished replacing 80% of the damaged equipment, but the plant was not yet receiving water and gas, according to a company official who spoke on condition of anonymity, citing protocol.

She said the company didn't know when production would return to pre-quake levels.

Honda, which halted its lines for two days until Friday, said it was being forced to suspend production on for an extra day for lack of components from Riken.

A Honda auto assembly plant, motorcycle factory and light car engine line will stay closed Monday, according to company spokesman Sakae Uruma.

Toyota Motor Corp. (7203.TO), Nissan Motor Co. (7210.TO), Mitsubishi Motors Corp. (7211.TO) and Mazda Motor Corp. (7261.TO), which have also halted domestic production for the week, said Friday they were unsure whether they could procure enough parts from Riken to restart their factories next week.

To speed up the process, Toyota, Honda and other car companies have dispatched a total of 650 workers to help with the cleanup, Riken said.

Analysts have said the delay - if short enough - probably would not affect domestic or overseas deliveries for big players such as Toyota, which has enough inventory to cover a few days of lost output.

Also Friday, delays threatened to spread to other sectors as construction machinery company Kubota Corp. (6326.TO), which also procures parts from Riken, said it was partially suspending production at four of its plants in Japan.

Earthquakes have previously hurt Japan's auto industry.

A 1995 quake that devastated the western city of Kobe forced a major break systems manufacturer to stop production.

The halt affected nine auto companies and caused total auto production for that year to fall by 40,000 vehicles, according to the Nikkei business daily.