Bahraini police on Sunday fired tear gas at protesters in Pearl Square, Manama, for the first time since demonstrators began an anti-regime sit-in there last month, witnesses said.
Several protesters were hurt after inhaling tear gas fired by riot police from a bridge overlooking the square, but security forces pulled out shortly after, witnesses said.
Almost a month into protests calling for deep political change in Bahrain, anti-government demonstrators and the Gulf kingdom's rulers appear to be at an impasse, with neither side backing down.
"I believe there is a stalemate," said Salman Shaikh, the director of the Brookings Doha Center. "The parties, from what I can see, still seem to be very far apart."
The demonstrations in Shia-majority, Sunni-ruled Bahrain broke out 14 February, part of a wave of protest movements across the Arab world after uprisings in Tunisia and Egypt that toppled those countries' long-time rulers.
But in this small, strategic archipelago which is home to the US Fifth Fleet, the situation is complicated by disparate demands on the scope of political change sought by protesters and various opposition groups.
Mainstream opposition movements led by the Islamic National Accord Association (INAA), the main Shia group, have stopped short of calling for the fall of the Al-Khalifa dynasty, which has ruled Bahrain for over 200 years. Instead, they are demanding major reforms including a new constitution and a fully elected legislature.
Three more hardline organisations — Wafa, Haq and Bahrain Freedom Movement —have formed a "Coalition for a Bahraini Republic" to push for the fall of the monarchy.
Protest marches and rallies, which are held almost daily and usually number around 1,000 people during the week — many more on the weekend — are dominated by anti-regime and anti-monarchy slogans.
Thousands of people protested outside King Hamad's Safriya Palace near Manama on Saturday, chanting slogans calling for the fall of the regime, and against the king and the monarchy.
But some protesters favour a constitutional monarchy along the lines of that in Britain, where the monarch has a largely ceremonial role. This idea has also been endorsed by mainstream opposition groups.
Bahrain was transformed from an emirate into a constitutional monarchy under a 2002 constitution. But the ruling family, especially the king, maintains significant power and the upper house of the legislature is appointed.
The security forces have killed seven people and wounded many more since protests began. But apart from using tear gas against stone-throwing activists on Friday, the authorities have not used force since the first week of unrest.
Although the government has announced economic and political initiatives aimed at assuaging protesters' anger, the opposition has dismissed such moves as cosmetic and inadequate.
Crown Prince Salman has been tasked with opening a dialogue with the opposition, but the INAA and other opposition groups have said they reject the offer unless the government first agrees to their preconditions.
US Defence Secretary Robert Gates, who visited the kingdom on Saturday, said he had advised Bahrain's leaders to move quickly or risk interference from Iran, the Shiite theocracy which lies a short boat ride away across the Gulf.
Gates said he also told King Hamad that given the "impulse behind the political and economic grievances across the region ... baby steps probably would not be sufficient.
"I told both the king and the crown prince that across the region I did not believe there could be a return to the status quo ante, that there was change, and it could be led or it could be imposed," he added.
Bahrain's rulers have promised to spend $5.32 billion on new housing and to recruit 20,000 employees to the Interior Ministry, while King Hamad has reshuffled his cabinet and ordered the release of some political detainees.
But activists have dismissed these moves as "too little, too late."
The danger of Sunni-Shia violence lurks beneath the surface. Residents said police broke up sectarian clashes south of the capital on 3 March, and there have been unconfirmed reports of other sectarian incidents.
The demonstrators continue to maintain their vigil in a tent city in Manama's Pearl Square, the epicentre of anti-government protests.
One of them, Zainab, an 18-year-old university student, insisted: "We will be here until we win."