(Adds Caracas rallies)
By Peter Murphy and Andrew Cawthorne
CARACAS, Feb 12 (Reuters) - Armed pro-government groups attacked and shot at people protesting against President Nicolas Maduro's government in western Venezuela, injuring five, activists said.
Men on motorbikes belonging to militant community groups known as "colectivos" attacked the demonstrators late on Tuesday in the Andean city of Merida, the activists said, the latest unrest over a series of anti-government protests in Venezuela.
There was no comment from government officials on the incident. They have been accusing hardline Venezuelan opposition leaders of promoting violent demonstrations as part of a wider strategy to bring down the 10-month-old Maduro government.
A human rights activists who works with the opposition party Popular Will said the five injured in Merida were aged between 15 and 34, and all had bullet-wounds.
"They were attacked by the colectivos while exercising their right to peaceful protest," Tamara Suju said.
Government supporters say student protesters have been throwing rocks, attacking government offices, and blocking roads in the city. Policemen have been injured during student-led protests in another western state, Tachira, officials say.
"They want to bring down the legitimate government that I lead. They are not going to achieve it," Maduro said in a speech late on Tuesday.
"They are going to damage Venezuela ... They should correct their behavior in time. If they don't ... I will apply the law and the constitution with absolute severity against coupsters, destabilizers and violent sectors, whoever they are."
RIVAL RALLIES IN CARACAS
The largest yet of the recent rallies began in Caracas on Wednesday, with several thousand opposition supporters gathering in a square amid a cacophony of chants, horns and whistles.
"You need therapy to live in Venezuela!" read one banner, held up by members of a university psychology department.
"I'm here to show my dissatisfaction with the government. I'm unhappy with the insecurity we are experiencing, the economic crisis and the shortages," said student Manuel Gonzalez, 22.
Thousands of government supporters held a rival rally in Caracas as part of Wednesday's "Youth Day" commemoration that celebrates the participation of students in a 19th century independence battle against colonial authorities.
"We are the young revolutionaries, hand-in-hand with the Venezuelan government," shouted one Maduro supporter, amid a crowd clad in the red colors of the ruling Socialist Party.
Some Caracas residents stayed at home for fear of violence.
Some 20 or so demonstrators have been arrested since Popular Will and another hardline opposition group began calling for street protests to promote the "exit" of Maduro two weeks ago.
Massive opposition protests in the past helped bring about a brief coup against Maduro's predecessor Hugo Chavez in 2002, but he returned after a 36-hour detention when the military swung behind him and supporters poured onto the streets.
The current protests in Venezuela have been much smaller in the past, and have split the opposition, where many favor a more moderate approach.
"While there are plenty of reasons to protest, there does not seem to be an agenda for the current wave. #LaSalida (The Exit) is not a strategy, it's a hashtag!" complained the pro-opposition blog Caracas Chronicles.
"The street protests, along with the public bickering they are engendering, are creating a false sense that our actions can undo the regime, while at the same time casting doubt on the opposition's unity." (Additional reporting by Javier Farias in Tachira; Writing by Andrew Cawthorne; Editing by Sophie Hares)