Bahrain's Shiite opposition warned Friday on the eve of elections that failure by the kingdom's Sunni rulers to loosen their grip on power could trigger a surge in violence.
The government of the key US ally said it was ready for dialogue with the opposition, which is boycotting Saturday's legislative and municipal polls, the first since a Shiite-led uprising nearly four years ago.
"The door to dialogue will never be shut, including with Al-Wefaq," Information Minister Samira Rajab said in an interview with AFP, referring to the main Shiite opposition movement.
The Shiite opposition's month-long uprising in early 2011 calling for democratic reforms was crushed by the authorities.
Hundreds of demonstrators took to the streets of the Shiite village of Diraz on Friday pledging to boycott the polls, with police firing tear gas to disperse them, witnesses said.
"Boycott! Boycott!" the demonstrators chanted.
Ali, a man in his 60s, said: "I will not vote so long as my neighbours have a son in prison or martyred" in the protests.
Shiite demonstrators frequently clash with security forces in villages outside the capital Manama and hundreds have been arrested and faced trial since the uprising.
The political rivals have struggled to bury their differences through a so-called "national dialogue" that fell apart despite several rounds of negotiations.
Al-Wefaq chief Sheikh Ali Salman told AFP on Friday that the opposition could only resume talks with the government if it agreed to implement reforms in line with a strict timetable.
"This has been our strategy in the past, it is our strategy today and will be our strategy tomorrow... in order to reach a consensus that would end the ruling family's monopoly of all power," he said.
Salman warned that failure to reach a political accord could spark an "explosion" of violence in Bahrain, home to the US Navy's Fifth Fleet and a partner in the US-led campaign against the Islamic State jihadist group.
"A huge terrorist threat hangs over all the countries (of the region) and unfortunately everything is possible... as long as the regime and the opposition do not reach a political agreement," he said.
The boycott stems from "the people's demand for democratic reforms," he said, predicting a maximum 30 percent turnout at the polls.
The electorate of almost 350,000 will be called to choose 40 deputies. Most of the 266 candidates are Sunnis.
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- Constitutional monarchy -
The opposition wants a "real" constitutional monarchy with an elected prime minister independent from the ruling Al-Khalifa royal family.
But the Saudi-backed Sunni dynasty which rules over the majority Shiite kingdom has rejected the demand.
Al-Wefaq was in October banned by a Bahraini court from carrying out any activities for three months for violating a law on associations.
The movement engaged in several rounds of talks with the authorities but refused to resume discussions in September despite a new proposal announced by Crown Prince Salman bin Hamad Al-Khalifa.
The proposal had five core elements, including the redefinition of electoral districts and permission for parliament to question the premier and his ministers.
The security forces, blamed for the deaths of dozens of protesters, would also be bound by new codes of conduct.
At the time, Al-Wefaq chief Salman said the proposal "ignores the legitimate demands of the people".
He said Friday he did not expect the opposition to reach an agreement with the government, following protests which he said had cost "at least 100 lives" over the past three years.
The information minister, for her part, insisted that Bahrain would not tolerate "chaos".
"Violence is not allowed. It is tantamount to terrorism," Rajab said.
She also denounced "foreign interference", saying it fanned tensions and stood in the way of an agreement with the opposition.
Bahrain has repeatedly accused Iran, which lies just across the Gulf, of backing the Shiite opposition.