Hong Kong riot police battled with thousands of pro-democracy protesters for control of the city's streets late Saturday and early Sunday, using pepper spray and batons to hold back defiant activists who returned to a protest zone that officers had partially cleared. The clashes are leading to a deepening sense of impasse between a government with limited options and a pro-democracy movement increasingly willing to confront police. The worst political crisis in Hong Kong since Britain handed the city back to China in 1997 entered its fourth week with no sign of a resolution despite talks scheduled for two hours on Tuesday between the government and student protest leaders.