Image copyright Reuters Image caption Passengers arrive at Washington's international airport in July after the Supreme Court

US President Donald Trump has expanded his controversial travel ban to include people from North Korea, Venezuela and Chad, citing security concerns.

The new, open-ended restrictions follow a review of information sharing by other countries, the White House said.

Iran, Libya, Syria, Yemen and Somalia remain under the travel ban. Sanctions previously placed on Sudan were lifted.

In a presidential proclamation, Mr Trump said the countries in the list had "inadequate" security protocols.

"I must act to protect the security and interests of the United States and its people," he said in the document, issued late on Sunday.

According to data available from the US State Department, 109 visas were issued to North Korean citizens in 2016, however, it is unclear how many actually travelled to the United States.

Mr Trump's original ban in March was highly controversial, as it affected six majority-Muslim countries, and was widely labelled a "Muslim ban".

Media playback is unsupported on your device Media caption Muslim students on Trump ban: 'I don't belong here'

It was subject to a range of legal challenges and several large-scale protests, and was due to be considered by the US Supreme Court on 10 October, having been partly reinstated in July.

But on Monday the Supreme Court postponed the October oral arguments, and instead called upon all parties challenging the White House to resubmit briefs to the court on whether the case should be dismissed.

The American Civil Liberties Union rights group said the addition of the new countries did not "obfuscate the real fact that the administration's order is still a Muslim ban".

The addition of North Korea and Venezuela now means not all nations on the list are majority-Muslim. The restrictions on Venezuelans apply only to government officials and their family members.

The Venezuelan foreign ministry on Monday described the new restriction as "a form of psychological and political terrorism".

Media playback is unsupported on your device Media caption Venezuelan Vice-President Tareck El Aissami calls US travel ban "a trophy" for a "subversive people"

The criteria for the new ban list are now based on vetting procedures and co-operation, and the restrictions have been "tailored" on a country-by-country basis:

The White House said North Korea did not co-operate with the US government "in any respect" and failed all requirements - and so all travel to the US by its citizens had been banned. However, officials acknowledged to US media that numbers of visitors were very low and the measure might have a limited impact

Chad, while an important counter-terrorism partner, did not share terrorism-related and other public information the US required - business and tourist visas for its nationals have been suspended

Only "certain Venezuelan government officials and their immediate family members" have been banned - its government has recently been hit with economic sanctions by the US, who now say it does not co-operate "in verifying whether its citizens pose national security or public-safety threats" and does not receive deported nationals willingly

Most of the restrictions come in the form of suspension of B-1 and B-2 business and tourist visas, and are not time-limited in the way that Mr Trump's former executive order was.

In a fact sheet accompanying Mr Trump's proclamation, the White House said that while Iraq also fell short of the required criteria, the country was not included in the new restrictions "because of the close co-operative relationship between the United States" and their part in fighting so-called Islamic State.

The restrictions come into effect on 18 October, but will not apply to those already in possession of a valid visa, the White House said.