WASHINGTON, Sept. 24 (Xinhua) -- U.S. President Donald Trump on Sunday expanded a travel ban to include visitors from the Democratic People's Republic of Korea (DPRK) in East Asia, Venezuela in Latin America and Chad in central Africa.

Meanwhile, Trump kept the controversial travel ban which was set to expire Sunday on five of six countries, namely Iran, Libya, Somalia, Syria and Yemen, and lifted restrictions on Sudan.

The new travel restrictions are expected to take effect on Oct. 18 and will be indefinite, according to president's proclamation, which the White House said has the same force as an executive order.

The administration said the new standards are based on factors such as whether countries issue electronic passports with embedded traveller information or share information about travelers' terror-related and criminal histories.

"As president, I must act to protect the security and interests of the United States and its people," Trump said in the proclamation.

Days ago, the U.S. president called for a "tougher" travel ban after a bomb partially exploded on a London subway.

"The travel ban into the United States should be far larger, tougher and more specific-but stupidly, that would not be politically correct!" Trump tweeted last week.