More US states have joined Hawaii in a legal challenge against president Donald Trump’s revised travel ban.

New York maintains the new directive is a ban on Muslims while Washington says it is harmful to the state. Oregon and Massachusetts later also joined.

Trump signed an executive order placing a 90-day ban on people from six mainly Muslim countries on Monday.

The ban begins next week (March 16), with the White House saying it is “very confident” of winning in court.

The revised ban bars new visas for people from Somalia, Iran, Syria, Sudan, Libya and Yemen. It also temporarily blocks all refugees.

The previous order, which was signed by Trump in January, was blocked in federal courts and sparked mass protests as well as confusion at airports.

But critics maintain the revised travel ban discriminates against Muslims.

New York attorney general Eric Schneiderman said after announcing his legal challenge: “President Trump’s latest executive order is a Muslim ban by another name, imposing policies and protocols that once again violate the equal protection clause and establishment clause of the United States constitution.”

Washington state attorney general Bob Ferguson, who was the first to sue over the original ban, said he would ask a federal judge to rule that the temporary restraining order halting the first travel ban “remains in effect,” the BBC reported.

“We’re asserting that the president cannot unilaterally declare himself free of the court’s restraining order and injunction,” he said.