KATHMANDU — Tens of thousands of protesters filled the streets of Nepal’s capital on Monday to vent anger over a government decision to block most major social media platforms, forcing riot police to retreat and prompting authorities to impose a local curfew.

Protesters pushed through barbed wire and surrounded the Parliament building, chanting “Stop the ban on social media, stop corruption not social media,” as police fired tear gas and used water cannon. Authorities said they declared a curfew for Monday around Parliament, the government secretariat, the presidential residence and other key parts of the city as the situation grew tense.

The government said platforms including Facebook, X and YouTube have been blocked because they failed to register their companies locally and submit to oversight requirements. Authorities have issued repeated notices to about two dozen social networking services used widely in Nepal; those that did not register were blocked beginning last week. TikTok, Viber and three other platforms have registered and continue to operate without interruption, officials said.

The moves follow the introduction of a bill sent to Parliament for debate that aims to ensure digital platforms are “properly managed, responsible and accountable.” Among other measures, the draft legislation would require companies to appoint a liaison office or point of contact within Nepal. Government officials have framed the measure as a way to regulate content and bring foreign platforms under local law.

Rights groups, opposition politicians and media freedom advocates have criticized the step as a tool for censorship that could be used to punish government critics and curtail free expression. The online backlash and street protests were driven partly by younger demonstrators, with Monday’s rally widely described as the “protest of Gen Z” — referring to people born roughly between 1995 and 2010.

Protests and restrictions on platforms are not new in Nepal. In 2023, the government banned the video-sharing app TikTok, saying it disrupted “social harmony” and spread indecent material; the ban was lifted last year after TikTok officials pledged to comply with local regulations. Nepal also enacted a ban on pornographic websites in 2018.

Officials say the registration requirement is meant to make platforms accountable for removing illegal content and responding to local authorities, but critics say the law’s broad language and enforcement tools could be used to suppress dissent. The debate in Parliament is expected to focus on the balance between regulation and rights, though lawmakers had not concluded deliberations as of Monday.

Police and government statements gave no immediate tally of arrests or injuries. The protest movement pushed into the area around the Legislature and forced security forces to pull back into the complex; authorities continued to urge calm and stressed the curfew boundaries.

As demonstrations continued into the evening, the political standoff highlighted tensions in a country that has seen recurring instability since it became a republic more than a decade ago. Advocates for internet freedom said the dispute over registration and oversight of global platforms could have broader implications for civic space and political debate in Nepal, while the government maintained that the measures are necessary to enforce national laws online.

The situation remained fluid, with authorities monitoring protests and parliamentary debate on the proposed internet regulations expected to continue in the coming days.