YANGON, Oct 2 (Reuters) - Myanmar's military junta announced a two-hour reduction on Tuesday in an overnight curfew imposed on its main city last week as it countered the biggest anti-government protests in 20 years. Louspeaker trucks driving through the streets of Yangon said the curfew would now run from 10 pm to 4 am (1430 GMT to 2130 GMT) instead of 9 pm to 5 am (1330 GMT to 2230 GMT). The reduction is another sign of the military regime's confidence at having crushed the uprising, the biggest challenge to its authority since 1988 when the army killed an estimated 3,000 people in a crackdown stretching over several months.