Human rights  organizations announced Friday they are suing the Trump administration over the latest version of the president's controversial travel ban, continuing a long-running legal battle over the restrictions.

At the forefront of the challenge is the American Civil Liberties Union (ACLU), which along with partner organizations submitted a letter to the US District Court in Maryland seeking to amend an existing lawsuit they already filed.

The new travel ban, unveiled by the White House late Sunday, forbids citizens of seven countries from travelling to the United States -- citing national security reasons.

Under the ban, citizens of Yemen, Syria, Libya, Iran, Somalia, North Korea and Chad are all prohibited from entering the US.

Also suspended are certain Venezuelan government officials and their families, due to what the US called poor security and a lack of cooperation with American authorities.

The new ban "is still a Muslim ban at its core, and it certainly engages in discrimination based on national origin, which is unlawful," ACLU director Anthony Romero said Friday.

"Adding a few North Koreans and a tiny group of Venezuelan officials doesn’t paper over the original sin of the Muslim ban. We'll see President Trump in court — again," he added.

The second version of the travel ban was the subject of numerous court battles, and was poised for examination by the Supreme Court in Washington on October 10.

But the court cancelled the scheduled hearing Monday while it considers whether the new travel ban renders it irrelevant.