KATHMANDU -- Riot police in the Nepalese capital Kathmandu fired tear gas on Sunday to quell Maoist protesters who have staged a week of street rallies in the city demanding the government step down.

The Maoists had enforced a general strike closing all shops and offices across the country, but they abandoned the tactic on Friday amid public fury at the restrictions.

Thousands of left-wing protesters remain in Kathmandu as pressure builds on the coalition government ahead of an end-of-May deadline for a new constitution seen as crucial to ensuring lasting peace in Nepal.

"Twelve policemen have been injured in scuffles, and dozens have also been injured on the Maoist side," police spokesman Bigyan Raj Sharma told AFP.

"Police went in to rescue an alleged infiltrator who was being beaten up by Maoist protesters," he said, adding that police had been attacked with stones and sticks.