By Kevin Krolicki and David Bailey

DETROIT (Reuters) - General Motors Corp (GM.N: Quote, Profile, Research) union workers at a Kansas assembly plant making the hot-selling Chevrolet Malibu went on strike Monday morning, the automaker and the union said.

The plant in Fairfax, Kansas, employs about 1,800 hourly workers who walked out at 9 a.m. CDT (1400 GMT) Monday morning. The strike came after GM and United Auto Workers Local 31 failed to reach agreement on plant-level rules following a four-year national contract approved last year.

The Kansas strike is one of several labor disputes to hit GM in recent weeks, crimping production for the No. 1 U.S. automaker and threatening some of its better-selling vehicles.

GM shares fell 3 percent after news of the strike broke.

UAW workers remain on strike at GM's Lansing Delta Township plant in Michigan where the company builds its crossover vehicles, like the Buick Enclave.

GM makes the 2008 Malibu in Kansas and at a second plant in Orion, Michigan. UAW workers at the Michigan plant also assemble the Pontiac G6 and have reached a local contract agreement with GM.

The Malibu has been a commercial and critical success for GM at a time of slumping overall demand, selling for higher prices on average and at a faster rate than the model it replaced since its launch late last year.

"We are disappointed that UAW Local 31 has taken the strike action at Fairfax," GM spokesman Dan Flores said. "From a GM perspective, we are going to remain focused on reaching an agreement as soon as we can and hope this is a very short disruption."