Brazil's Supreme Court on Thursday ordered Elon Musk's X to suspend access to the social network, after service was restored despite a ban, or face a daily fine of over US$900,000.

Formerly Twitter, the platform was banned last month in Latin America's largest nation, but access to the phone app returned on Wednesday in what the government slammed as a deliberate violation of the suspension order.

X said the return of its service was "inadvertent and temporary".

Judge Alexandre de Moraes said in a court order that a "recalcitrant" X had "unlawfully, persistently and intentionally" failed to respect judicial orders, and would face a daily fine of 5 million reais, or US$913,000 until it again suspends its service.

Moraes also ordered state telecommunications agency Anatel to take all necessary measures to once again block access to the social network.

The high-profile judge has been engaged in a long feud with South African-born billionaire Musk, as part of his drive to crack down on disinformation in Brazil.

Last month he ordered the suspension of X after Musk refused to remove dozens of right-wing accounts accused of spreading fake news, and then failed to name a new legal representative in the country as ordered. (AFP)