About 250 International Paper Co. employees will be laid off Sunday because of an accident that will shut down the plant for up to two weeks.

The shutdown follows another earlier this summer in which many of the same employees were sent home because of a slowdown in the market for kraft linerboard, which is produced at the mill.

The plant accident occurred Wednesday night, mill spokesman Ray McLaurin said, when acid got into a boiler, causing both of the plant’s boilers to be turned off.

He said Thursday that employees were investigating the source of the acid.

Repairs are expected to take about two days, but the layoffs will last about two weeks because the linerboard market is still soft, McLaurin said.

“The rest of the down time will be for market reasons,” he said.

The Vicksburg mill employs about 365 people. Many of those who remain at the mill during the shutdown are office personnel, McLaurin said.

When the mill closed for nearly three weeks on June 25, International Paper cited a downturn in the international market for linerboard. McLaurin said that remains a problem.

He noted that several other IP mills, including two in Louisiana, Alabama and Georgia, have been forced to curtail production this year. Also, a mill in Springhill, La., which makes plywood, will shut down effective Monday and the mill in Natchez was put up for sale.

The mill in Springhill is part of IP’s wood products division in the Building Materials Group.

Kraft linerboard is used in the manufacture of corrugated cartons. The local mill also makes a substance called tall oil, which is used in a variety of products.