Police on Monday detained 104 striking workers protesting low wages at a Samsung Electronics plant in southern India as they were planning a protest march without permission, with the dispute disrupting output at the key factory for the past week.

The detention marks an escalation of a strike by workers at a Samsung home appliance plant near Chennai in the state of Tamil Nadu. Workers want higher wages and have stopped work at the plant that contributes roughly a third of Samsung’s annual India revenue of $12 billion.

The Samsung protests have cast a shadow on Indian Prime Minister Narendra Modi’s plan of courting foreign investors to “Make in India” and his goal of tripling electronics production to $500 billion within six years.

Lured by cheap labor, foreign companies are increasingly using India for manufacturing to diversify their supply chain beyond China.

On Monday, the workers planned to start a protest march, but were detained as no permission was given since there are schools, colleges and hospitals in that area, said senior police officer of the Kancheepuram district K. Shanmugam.

“It is the main area which would become totally paralyzed and [the protest would] disturb public peace,” he said.

“We have detained them in wedding halls as all of them can’t be in stations,” he said.

Samsung workers since last week have been protesting at a makeshift tent near the plant, demanding higher wages, recognition for a union backed by influential labor group the Centre of Indian Trade Unions (CITU), and better working hours.

Samsung is not keen to recognize any union backed by a national labor group such as the CITU, and talks with workers, as well as state government officials, have not yielded resolution.

The CITU Tamil Nadu Deputy General Secretary, S. Kannan, condemned the police action, saying “This is an archaic move by the state government.”

Despite Monday’s police action, 12 union groups, including one affiliated with the ruling party of Tamil Nadu, said in a public notice dated Sept. 11 that they will stage a protest in support of the striking workers in Chennai on Wednesday, a move that could intensify the tensions between the company and the workers.

“We are going ahead with Wednesday’s protest … no changes to the plan,” said A. Jenitan, a deputy district secretary for the CITU.

The protests add to Samsung’s challenges in India, a key growth market.

The South Korean company is planning job cuts of up to 30% of its overseas staff in some divisions, including in India. And India’s antitrust body has found Samsung and other smartphone companies colluded with e-commerce giants to launch devices exclusively, violating competition laws, Reuters has reported.

Samsung did not respond to a request for comment on Monday, but on Friday said it has initiated discussions with workers at the Chennai plant “to resolve all issues at the earliest.”

Video footage from Reuters partner ANI showed dozens of Samsung workers wearing the company uniform of blue shirts being transported in a bus to a hall.

The Samsung plant employs roughly 1,800 workers and more than 1,000 of them have been on strike. The factory makes appliances such as refrigerators, TVs and washing machines. Another Samsung plant that makes smartphones in the northern state of Uttar Pradesh has had no unrest.

The police also detained one of CITU’s senior leaders, E. Muthukumar, who was leading the Samsung protests at the factory near Chennai, according to the CITU’s Jenitan.

Kancheepuram police official Shanmugam said there was no timeline as to how long the workers will be detained.