(Adds company comments)
LUSAKA, Jan 4 (Reuters) - Zambian workers have downed tools at a mine and copper processing plant belonging to Konkola Copper Mines (KCM), a unit of Vedanta Resources VED.L , in a dispute over the pace of wage talks, a union official said on Wednesday.
The stoppage at the Konkola mine in Chililabombwe in northern Zambia began after a Dec. 31 target for completing talks on a 2017 pay settlement passed without agreement.
"The day shift workers have not entered the plant, they are protesting the slow pace of salary negotiations," National Union of Mine and Allied Workers (NUMAW) trustee Jonathan Musukwa told Reuters.
The company is not saying what the impact will be on production but the workers locked the gates to block day-shift operations.
Union sources said KCM officials were meeting the minister of labour and the unions to try and resolve the impasse.
The company said the strike was illegal.
"KCM regrets that a handful of employees at the Konkola underground mine in Chililabombwe have decided to go on an illegal work stoppage demanding increases in pay," the company said in a statement.
"This is in contravention of labour laws since wage negotiations are still under way between management and the unions and no dispute has been declared."
KCM said management would continue to engage the unions to find a lasting solution to the problems the company was facing.
Chililabombwe is the largest plant operated by KCM, which produced 168,923 tonnes of finished copper in the financial year ended March 31, 2015.