July 19 (Reuters) - Anti-coup protesters in Myanmar held demonstrations on Monday to coincide with a public holiday to commemorate slain independence heroes, including the father of the country"s detained elected leader, Aung San Suu Kyi. Since the military seized power on Feb. 1 and arrested Suu Kyi and other senior members of her party, hundreds of people have been killed as the army quelled street protests and in clashes between soldiers and newly formed people"s militias. Monday also marked a record number of deaths from the coronavirus in Myanmar where the health service has largely collapsed since the coup as many medics joined a Civil Disobedience Movement to oppose the junta. read more In Yangon, military authorities held a tightly controlled ceremony for Martyrs" Day at a mausoleum dedicated to Aung San, Suu Kyi"s father and a national hero, who was assassinated alongside members of his cabinet on July 19, 1947. Drivers in Yangon blared their horns at 10:37 a.m., a tradition marking the time the independence leaders were killed. Last year, Suu Kyi laid a wreath at the same ceremony but this year only some relatives were present at the event that was also attended by the military-appointed Minister of Religious Affairs and Culture, Ko Ko. In Monywa, west of the city of Mandalay, anti-junta demonstrators held a march where they chanted "Martyrs never die. We are going to wash our feet with the blood of war dogs", in a reference to soldiers, photographs on social media showed. In Meiktila in central Myanmar, protesters held a banner in front of the Martyrs" Day memorial paying tribute to four other "martyrs" who had died in their district during recent demonstrations against the coup. Security forces have killed at least 914 people since the coup, according to the Assistance Association for Political Prisoners, an activists" group. The junta has disputed the figure and said many soldiers have also been killed. The military justified its coup by accusing Suu Kyi"s National League for Democracy party of manipulating last November"s vote to obtain a landslide victory, though the electoral commission at that time rejected its complaints. Suu Kyi is on trial in the capital Naypyitaw on charges that include illegal importation and possession of walkie-talkie radios and violating coronavirus protocols. She is also charged in a Yangon court with unspecified breaches of the Official Secrets Act, punishable by a maximum of 14 years in jail, and faces charges in Mandalay. Her legal team rejects all of the charges. Myanmar registered a record 281 COVID-19 deaths on Monday, and 5,189 new infections, the state-run MRTV Television reported, citing health ministry figures. Coronavirus cases started to rise in June and have soared in the past few weeks. Medics and funeral services say the real toll is much higher than the military-controlled government"s figures, and crematoriums are overloaded. The United Nations said on Sunday it was stepping up efforts to combat an "alarming spike" in COVID-19 infections in the country, including helping to bolster oxygen supplies which are running short.