The maker of semiconductor assembly and packaging equipment said that torrential rains affected its main production facility in Shah Alam in Malaysia and halted the assembly of products with a value of around 25 million euros ($28 million).

"First estimates of one-time costs associated with materials and labor necessary to repair or reproduce any systems affected are in the range of 4-6 million euros and will be taken as a charge to fourth quarter earnings," the group said in a statement.

BESI said it did not expect estimated costs to repair the affected building and production related equipment to exceed 2 million euros.

Malaysian emergency services, reinforced by civilian volunteers, on Sunday rescued 21,000 people displaced by flooding from torrential rain in seven states.

The company now forecasts around a 15-20% fall in fourth-quarter revenue versus the third quarter compared with prior guidance of a decrease of 5-15%.

But BESI said it expected its fourth-quarter orders to reach around 180-190 million euros, up from 157.3 million euros recorded in the fourth quarter of last year.

BESI shares were down 4.6% to 70.32 euros at 1358 GMT.

The company was not immediately available to comment which of its customers could be affected by the floods.

According to company's latest annual report, its customers include ASE, Amkor, Forehope, Foxconn, Greatek, Huatian, Infineon, JCET/STATS ChipPAC, LG Innotek, Micron, NXP, STMicroelectronics, TDK Electronics and TFME.

($1 = 0.8887 euros)

(Reporting by Anait Miridzhanian; Editing by Jane Merriman and Mark Potter)