TAIPEI (Reuters) - Taiwan's AU Optronics <2409.TW> said on Thursday it has suspended work at three factories in the northern part of the island following an earthquake that struck the previous day, though contract chip makers TSMC <2330.TW> and UMC <2303.TW> said all operations remained normal.

AU Optronics, the world's No.4 flat panel maker, said in a statement it was still evaluating how much capacity would be affected.

The quake, with a preliminary magnitude of 4.9, shook Taiwan on Wednesday. No casualties or damage were immediately reported, the central weather bureau said.

AU supplies major brands such as Hewlett-Packard , Dell Inc and Sony Corp <6758.T>.

(Reporting by Faith Hung and Clare Jim; Editing by Kim Coghill)