President Donald Trump has directed the United States government to pause the US green card lottery system after authorities revealed that the suspect in recent shootings at Brown University and the Massachusetts Institute of Technology (MIT) entered the United States through the scheme.

The directive, announced late Thursday by Homeland Security Secretary Kristi Noem, instructs the US Citizenship and Immigration Services (USCIS) to halt the programme immediately, the Associated Press reports.

Noem said the suspected gunman “should never have been allowed in our country,” referring to the 48-year-old Portuguese national Claudio Manuel Neves Valente.

Neves Valente is accused of killing two students and wounding nine others at Brown University, then separately fatally shooting an MIT professor, before being found dead from a self-inflicted wound on Thursday evening, officials said.

Valente reportedly obtained legal permanent residence status in 2017.

The Diversity Visa (DV1) lottery programme, popularly known as the US green card lottery system, was created by the US Congress as part of the Immigration Act of 1990. The programme grants up to 50,000 green cards each year to people from countries with historically low US immigration rates. Winners are selected by random draw and undergo standard consular vetting before entry.

“Most lottery winners reside outside the United States and immigrate through consular processing and issuance of an immigrant visa,” the USCIS website reads.

Trump has criticised the diversity visa lottery for years on national security grounds, calling for its termination in his previous term.