YANGON, Feb. 5 (CNA) - US President Joe Biden called on Myanmar's generals to "relinquish power" on Thursday (Feb 4) and demanded they free civilian leaders detained in this week's coup, as his administration said it was considering sanctions.

Washington has led international condemnation of Monday's putsch, which saw democratic leaders including Aung San Suu Kyi detained and ignited fears that the military will drag 54 million people back to the decades of military rule.

"There can be no doubt: in a democracy, force should never seek to overrule the will of the people or attempt to erase the outcome of a credible election," Biden said from Washington, in his first major foreign policy speech as president.

"The Burmese military should relinquish power they have seized, release the advocates and activists and officials they have detained, lift the restrictions in telecommunications, and refrain from violence."

Biden spoke hours after his national security adviser, Jake Sullivan, said the White House is "looking at specific targeted sanctions both on individuals and on entities controlled by the military that enrich the military". He did not give further details.

The US warnings came after Myanmar's generals ordered internet providers to restrict access to Facebook on Thursday, as people flocked to social media to voice opposition and share plans for disobedience.

Facebook-owned apps such as Instagram and WhatsApp were also disrupted.

"We have digital power ... so we've been using this since day one to oppose the military junta," said activist Thinzar Shunlei Yi, who is behind a so-called "Civil Disobedience Movement" fanning out across social media platforms.

Telenor, one of the country's main telecoms providers, confirmed authorities had ordered it to "temporarily block" Facebook access.

The Norwegian-owned company said it had to comply but "does not believe that the request is based on necessity and proportionality, in accordance with international human rights law".

Facebook confirmed access "is currently disrupted for some people" and urged authorities to restore connectivity.