The State Department is now requiring nearly all applicants for US visas to submit their social media usernames, previous email addresses and phone numbers.

Key points: Travellers will have to surrender their handles for Facebook, Twitter, Instagram and YouTube

Travellers will have to surrender their handles for Facebook, Twitter, Instagram and YouTube Critics say it will unfairly target immigrants and travellers from Muslim-majority countries

Critics say it will unfairly target immigrants and travellers from Muslim-majority countries The change is expected to affect about 15 million foreigners who apply for visas to the US

It's a vast expansion of the Trump administration's enhanced screening of potential immigrants and visitors.

The department says it has updated its immigrant and non-immigrant visa forms to request the additional information, including "social media identifiers".

The change, which was proposed in March 2018, is expected to affect about 15 million foreigners who apply for visas to enter the United States each year.

"National security is our top priority when adjudicating visa applications, and every prospective traveller and immigrant to the United States undergoes extensive security screening," the department said.

"We are constantly working to find mechanisms to improve our screening processes to protect US citizens, while supporting legitimate travel to the United States."

A screenshot of the new US visa question showing the types of social media platforms for which travellers will be required to provide their usernames. ( Twitter: Greg Siskind )

The new visa application forms list a number of social media platforms — including Facebook, Instagram, Twitter, Reddit, YouTube and Weibo — and require the applicant to provide any account names they may have had on them over the previous five years.

They also give applicants the option to volunteer information about social media accounts on platforms not listed on the form.

Hina Shamsi, director of the American Civil Liberties Union's National Security Project, said there was no evidence social media monitoring was effective and that it could have a "chilling" effect on freedom of speech and promote self-censorship online.

The ACLU said there is a real risk that social media vetting will unfairly target immigrants and travellers from Muslim-majority countries. ( Reuters: James Lawler Duggan )

"This attempt to collect a massive amount of information on the social media activity of millions of visa applicants is yet another ineffective and deeply problematic Trump administration plan," she said in a statement.

"There is a real risk that social media vetting will unfairly target immigrants and travellers from Muslim-majority countries for discriminatory visa denials, without doing anything to protect national security."

Wider net for scrutiny

The social media changes are expected to impact 15 million travellers to the US — including Australians. ( ABC News: Melanie Vujkovic )

Social media, email and phone number histories had only been sought in the past from applicants who were identified for extra scrutiny, such as people who had travelled to areas controlled by terrorist organisations.

An estimated 65,000 applicants per year had fallen into that category.

The department says collecting the additional information from more applicants "will strengthen our process for vetting these applicants and confirming their identity".

The new rules apply to virtually all applicants for immigrant and non-immigrant visas.

When it filed its initial notice to make the change, the department estimated it would affect 710,000 immigrant visa applicants and 14 million non-immigrant visa applicants, including those who want to come to the US for business or education.

In addition to their social media histories, visa applicants are now asked for five years of previously used telephone numbers, email addresses, international travel and deportation status, as well as whether any family members have been involved in terrorist activities.

Only applicants for certain diplomatic and official visa types are exempted from the requirements.

AP