For more than three years Thailand has been gripped by a paralysing political crisis centred on former Prime Minister Thaksin Shinawatra.
Mr Thaksin was ousted from office in a military coup in September 2006, and the tug-of-war between his supporters and opponents has continued ever since.
Neither side can accept the other’s view of who should run the country, and each has staged long-running protests to push their cause.
When Democrat Party leader Abhisit Vejjajiva was chosen as prime minister in December, some Thais hoped the protests had finally come to an end. But it appears the crisis is far from over.
Who are the pro-Thaksin protesters?
Mr Thaksin still retains widespread support among the rural poor, who benefited from the populist policies he framed during his five years in power.
His supporters call themselves the United Front for Democracy Against Dictatorship (UDD), and are known for wearing distinctive red shirts.
The UDD says Prime Minister Abhisit Vejjajiva came to power illegitimately and is a puppet of the military. It wants Mr Abhisit to resign and call fresh elections.
The protesters’ tactics are similar to those used by anti-Thaksin protesters last year, which eventually led to the change of government.
How effective are their protests?
Since March 2009, the protesters have held sit-in protests outside government offices, and have occasionally prevented the cabinet from meeting.
They also forced the cancellation of a summit of the Association of South-East Asian Nations (Asean) in April. They stormed the venue in the seaside resort of Pattaya, causing huge embarrassment to the government.
A day later, protesters broke into the interior ministry and blocked busy roads in Bangkok.
Tens of thousands are camped around Government House, where the prime minister’s office is based.
What is the government’s response?
After the collapse of the summit, Prime Minister Abhisit declared a state of emergency and vowed to restore order.
A day later, troops moved in to clear protesters from a major intersection in the capital Bangkok, leading to clashes.
Protesters hurled petrol bombs and rocks and set fire to buses and tyres, while soldiers fired live rounds into the air and into the crowds of demonstrators causing dozens of injuries.
Despite rumours of splits within the army, the military has vowed to do what it takes to restore order.
The militant refused to act when the previous pro-Thaksin government imposed a state of emergency.
Who are the anti-Thaksin protesters?
The opponents of Mr Thaksin call themselves the Peoples’ Alliance for Democracy (PAD), and wear yellow shirts to proclaim their allegedly more pro-monarchist stance.
People in Thailand often wear yellow to show their allegiance to the king, and one of the protesters’ key claims is that Mr Thaksin is not as loyal to the king as they are.
The PAD is a loose grouping of royalists, businessmen and the urban middle class, led by media mogul Sondhi Limthongkul and Chamlong Srimuang, a former general with close ties to the king’s most senior adviser, Gen Prem Tinsulanonda.
The PAD accuses Mr Thaksin of corruption and nepotism during his time in power.
PAD protests were instrumental in setting the scene for a military coup which removed Mr Thaksin from office in 2006.
They repeated these rallies in 2008, to protest against the party in power at the time – the People Power Party (PPP), which was widely seen as a reincarnation of Mr Thaksin’s banned Thai Rak Thai party.
The protesters took over Government House for three months, and engineered a week-long siege of Bangkok’s main airports in December, crippling the country’s vital tourism industry.
Together with several court rulings against the PPP, they are credited with bringing down two of its governments – firstly the administration of Samak Sundaravej and then that of Mr Thaksin’s brother-in-law Somchai Wongsawat.
Now that a pro-Thaksin government is no longer in power, the PAD is keeping a close watch on the rising anger inside the UDD camp.
How did Mr Abhisit become prime minister?
Amid the turmoil of the airport blockade in December 2008, a Constitutional Court ruled that the PPP was guilty of electoral fraud and barred its leaders from politics for five years.
There seemed to be no way forward, but then a few Thaksin loyalists changed sides to join the other main party, the Democrats.
This enabled Democrat leader Abhisit Vejjajiva to form a new government and become the next prime minister without calling elections.
The Democrats are not openly allied to one group of protesters or the other, but in the past the party has been closely associated with elements of the PAD.
Mr Abhisit has been criticised for his choice of foreign minister, Kasit Piromya – an open supporter of the PAD movement and its airport blockade.
Where is Mr Thaksin now?
Mr Thaksin describes himself as a citizen of the world, and he is often in Dubai, China, the UK or Hong Kong.
If he comes back to Thailand, he faces two years in jail after being found guilty in a conflict of interest case.
His long-term aims are unclear. In the past he has said he will not re-enter politics, but he has also said he is needed to lead Thailand out of the economic crisis.
He remains actively involved in politics, through the rallies of his red-shirted supporters. These rallies have prompted a vague offer of talks from the Abhisit government, which he has so far rebuffed.
Despite being out of the country, Mr Thaksin has been egging his supporters on in the latest protests, giving regular addresses on video-link.