Maruti Suzuki India's strike at its Manesar plant in northern India is now estimated to have cost US$20m according to media reports.

An unnamed source speaking to Agence France Presse, said losses since the strike began last Saturday are between INR800m and INR900m.

The shut-down appears to have been triggered by a dispute concerning union recognition and is believed to have led to the loss of around 1,800 vehicles.

"There is no work at the Manesar plant. The workers have refused to come to work," the source is quoted as saying to AFP.

"There is no clear charter of demands. They cannot simply say they want a change," noted the source, who added no notice had been given.

V L Sachdeva, secretary AITUC (All India Trade Union Congress), which is backing the strike, was previously quoted as saying in the Business Standard publication : "The new union applied for a registration to the registrar of trade unions on Friday. 

"The next day, Maruti's management asked its workers to sign an undertaking that they will not be a part of the new union. We do not want the management interfering in our matters. We have met the labour minister and the labour commissioner. There is every likelihood that agitation will increase if demands are not met." 

The company was quoted as saying delivery and sales of cars were unlikely to be affected.