Nearly 20,000 workers across major Indian ports are likely to go on a strike from Wednesday to demand immediate settlement of pay revisions and pension benefits, union workers said on Tuesday.

The strike could delay shipments and back up cargoes at various ports, pushing up freight costs and exacerbating the existing congestion at other Asian and European ports.

"The negotiations are in a deadlock, as the labour federations are demanding wage raises in the region of 10.6%, while the government is stuck at 6%," Sathya Narayanan, a senior union member said.

The union workers met Sarbananda Sonowal, India's federal shipping minister, on Tuesday.

The shipping ministry formed a bipartite wage negotiation committee in March 2021, and the workers submitted their demands six months later, ahead of the expiration of the previous agreement in December of that year, according to a note signed by union leaders, and reviewed by Reuters.

Although the wage negotiation committee met seven times, it failed to meet the port workers' demands, the note said.

The workers' group agreed to call for a strike after a meeting this month in Thoothukudi, a port city in the southern state of Tamil Nadu.

Ports such as Chennai, Cochin and Mumbai, with a combined cargo handling capacity of 1.62 billion metric tons annually, are expected to be hit by the strike.

"The port strike is proposed in an extremely difficult time where exporters are presently struggling to meet shipping schedules for Christmas season" said K. Unnikrishnan, joint director general of Federation of Indian Export Organisations.

(Reporting by Praveen Paramasivam in Chennai; editing by Mayank Bhardwaj and David Evans)