Immigration activists claimed on Thursday that the Immigration and Customs Enforcement (Ice) agency had locked 20 detained hunger strikers and their supporters in solitary confinement.

Ice denied exacting any revenge, claiming those moved to solitary had tried to intimidate others into joining the strike.

“While Ice fully respects the rights of all people to express their opinion without interference, when these expressions infringe on the civil rights of others Ice has an obligation to act,” it claimed.

At least 750 detainees participated in a hunger strike about a month ago to protest against immigration laws and the conditions at the Northwest Detention Centre in Tacoma, Washington, which houses nearly 1,300 people facing deportation.

Some began a renewed hunger strike on March 24.

Three days later, guards asked several if they wanted to meet an assistant warden.

After they raised their hands, they were handcuffed and placed in solitary confinement, activists allege.

The American Civil Liberties Union (ACLU) of Washington and Columbia Legal Services sued Ice and said they are seeking a restraining order to halt the practice.

“Retaliating against and punishing immigrant detainees engaged in peaceful protests is an unlawful attempt to chill free speech rights,” ACLU legal director Sarah Dunne said.

“Like all civil detainees, they have free speech rights protected by the Bill of Rights.”

Three detainees named as plaintiffs said they had done nothing to intimidate others.

The strikers have sought an end to deportations and better conditions at the centre.