Martial law was declared in parts of Myanmar's second largest city Mandalay Monday, after hundreds of thousands rallied across the country against the coup and the military issued a stern warning against further protests. The orders cover seven townships in Mandalay, banning people from protesting or gathering in groups of more than five, and a curfew will run from 8 pm until 4 am, the general administration department said in a statement. Anti-coup protesters marched in towns and cities across Myanmar, demonstrating for a third straight day against the military's removal and detention of elected leader Aung San Suu Kyi a week ago. In the biggest city of Yangon, a group of saffron-robed monks marched in the vanguard of Monday's protest with workers and students. They flew multi-coloured Buddhist flags alongside red banners in the colour of Ms Suu Kyi's National league for Democracy, witnesses said. "Release Our Leaders, Respect Our Votes, Reject Military Coup," said one sign. Other signs read "Save democracy" and "Say No to Dictatorship". Many protesters wore black. Calls to join protests and to back a campaign of civil disobedience have grown louder and more organised since last Monday's coup, which drew widespread international condemnation. Protests that swept the country on Sunday were the biggest since the "Saffron Revolution" led by Buddhist monks in 2007 that helped prompt democratic reforms that were upended by the February 1 coup. "Marchers from every corner of Yangon, please come out peacefully and join the people's meeting," activist Ei Thinzar Maung urged followers on Facebook, using VPN networks to rally protesters despite a junta attempt to ban the social media network. Thousands marched in the coastal city of Dawei, in the south-east, and in the Kachin state capital in the far north, where protesters were dressed head to toe in black. So far gatherings have been peaceful, unlike bloody crackdowns during widespread protests in 1988 and 2007. A convoy of military trucks was seen entering Yangon late on Sunday, raising fears that could change. The junta has not commented on the protests and state television has not mentioned them. The military rulers lifted a day-long internet ban at the weekend that prompted even more anger in a country fearful of returning to the isolation and even greater poverty before a transition to democracy began in 2011. Activists Maung Saungkha and Thet Swe Win posted on their Facebook pages that police had been to search for them at their homes, but that they were not there and were still free. In addition to the street protests, a campaign of civil disobedience has begun, started by doctors who were later joined by some teachers and other government workers. "We request government staff from all departments not to attend work from Monday," said activist Min Ko Naing, a veteran of the 1988 demonstrations that first brought Ms Suu Kyi to prominence. Ms Suu Kyi, 75, won the Nobel Peace Prize in 1991 for campaigning for democracy, and spent nearly 15 years under house arrest during decades of struggling to end almost half a century of army rule. She has been kept incommunicado since army chief Min Aung Hlaing seized power in the early hours of February 1. She faces charges of illegally importing six walkie-talkies and is being held in police detention for investigation until February 15. Her lawyer said he has not been allowed to see her. The UN Security Council called for the release of Ms Suu Kyi and other detainees last week and the United States is considering targeted sanctions. "Protesters in Myanmar continue to inspire the world as actions spread throughout the country," Thomas Andrews, the UN special rapporteur on Myanmar, said on Twitter. "Myanmar is rising up to free all who have been detained and reject military dictatorship once and for all. We are with you."