NAYPYIDAW (REUTERS) - Myanmar's military rulers have threatened to jail anti-coup protesters who take part in a "silent strike"on Tuesday (Feb 1), a year since the generals seized power, as the United States, Britain and Canada imposed new sanctions.

The South-east Asian country has been in chaos since Nobel laureate Aung San Suu Kyi and other figures from her National League for Democracy (NLD) party were rounded up in raids, accused by the junta of rigging a 2020 election the NLD won.

The overthrow of Ms Suu Kyi's government triggered huge street protests last year and the security forces killed hundreds in crackdowns that ensued leading to the formation of "people's defence forces" to take on the well-equipped army.

In recent days, activists have urged people to stay indoors and businesses to close on Tuesday.

"We might be arrested and spend our life in jail if we're lucky. We might be tortured and killed if we're unlucky," said youth activist Nan Lin, who hoped the strike would send a message to the junta.

A spokesman for the ruling military did not respond to telephone calls seeking comment.

State media reported military ruler Min Aung Hlaing had on Monday extended a state of emergency for six months to facilitate promised elections.

"It was necessary to set the right track for the genuine, disciplined multi-party democracy," Gen Min Aung Hlaing said in a report in the Global New Light of Myanmar, where he talked about the threat from "internal and external saboteurs" and "terrorist attacks and destruction".

The state-run newspaper said the military government would strive to hold new elections once the situation was "peaceful and stable", without giving a date.

In the northern city of Myitkyina, a photograph of a sign put up by the military warned residents not to join the silent protest or face jail terms of up to 20 years, though images of the city posted on social media on Tuesday showed largely deserted streets.

In the main city of Yangon, photographs on a social media page put up by strike organisers showed a small protest where people threw red paint on the ground.

The impact of the calls for a nationwide strike was not immediately clear.

At least four people were arrested in the central town of Pathein for inciting silent protests on social media, the Ayarwaddy Times reported.

International pressure

UN Secretary-General Antonio Guterres, in comments ahead of the coup anniversary, urged the junta to allow greater humanitarian access.

The junta has accused the United Nations of bias and interference and is refusing to bow to international pressure, despite a corporate retreat from Myanmar and sanctions, the latest on Monday, when the United States, Britain and Canada blacklisted more individuals linked to the junta.

For ordinary Myanmar people, life since the coup has become a grind, with the economy withering, regular power cuts and Internet curbs and, for some, a constant fear of being detained.

Security forces cracking down on dissent have killed at least 1,500 people and arrested 11,838 since the coup, according to the Assistance Association of Political Prisoners, an activist group cited by the United Nations.

The junta disputes the death toll.

Ms Suu Kyi, 76, is on trial in more than a dozen cases that carry a combined maximum sentence of more than 150 years in prison, charges that critics say are designed to ensure she can never return to politics.

In a joint statement, the foreign ministers of countries including Australia, Britain, South Korea, the United States and Canada, as well as the European Union, urged the international community to cease the flow of "arms, material, dual-use equipment, and technical assistance" to the Myanmar military.

An internationally backed diplomatic effort led by the Association of South-east Asian Nations (Asean) has faltered, with the junta's failure to honour its commitment to end hostilities and support dialogue frustrating members, including Singapore.

"Conditions in Myanmar for the people continue to deteriorate," its Foreign Ministry said in a statement marking the anniversary, which demanded Ms Suu Kyi and all political prisoners be freed.