Striking miners in South Africa could face the sack if they defy a union agreement to return to work for another day.They have been given until Tuesday afternoon to return to work.The bulk of the 3,000 members of the Association of Mineworkers and Construction Union (AMCU) - who led the so-called wildcat strike - have continued their protest.South Africa’s labour mediation committee has extended the deadline to Tuesday for workers at the world’s third largest platinum mine to return to work in order for salary negotiations to start.The workers, who have been on strike for a month, have vowed to stay off the job until they receive wages of $1,500 a month, double what they now earn.The committee says its "facilitation is dependent on a return to work by all workers” and threatened to leave the miners to deal with Lonmin managers.Only about 1,700 workers clocked in for their shift on Monday while thousands marched for higher wages after the committee earlier issued a Monday deadline.Hundreds of striking miners marched on Monday in defiance of the agreement signed by the mine management and the main National Union of Mineworkers (NUM).‘Put down the tools’Al Jazeera’s Mike Hanna, reporting from Mrikana, said: "One group of miners continue to insist they will not return to work until an agreement is reached on increasing their wages.”"It’s once again one group of striking miners coming up against mine owners. No progress whatsoever in weeks of negotiations in a bid to end the strike,” he said.Tensions have been high at the mine since 34 of the protesting workers were shot and killed by police last month.