Latin American and Caribbean leaders have come to an agreement supporting Argentina over sovereignty of the Falkland Islands, reports say.
The leaders are to approve a document supporting Argentina in its territorial dispute with the British government.
No official statement has been made but it is thought the document was drawn up behind closed doors at a regional summit in Cancun in Mexico.
The announcement comes as a British rig began drilling for oil off the islands.
According to reports from Cancun, Argentine President Cristina Kirchner says her government has won the backing of other regional leaders in its dispute with the UK over the territory in the South Atlantic.
The Mexican President, Felipe Calderon, is reported to have said that a document has been drawn up behind closed doors giving Argentina unanimous support.
The BBC's Andy Gallacher in Cancun says that any broad agreement at the summit could put more pressure on the British government in what has become an escalating diplomatic row.
Leaders at the summit, between the Rio Group and the Caribbean Community (Caricom), are also said to have discussed plans for a new pan-American alliance which would exclude Canada and the United States.
The new grouping would serve as an alternative to the Organisation of American States (OAS), the main forum for regional affairs in the past 50 years.
"It's time to realise the unity of Latin America and the Caribbean," said Mr Calderon, asking the attending leaders and foreign ministers to put aside their political differences.
'Legitimate right'
The British rig, The Ocean Guardian, 100km (62 miles) north of the Falklands, started drilling on Monday, despite fierce opposition from Argentina.
Desire Petroleum, which is carrying out the drilling, said operations had started on the Liz 14/19-A exploration well at 1415 GMT.
Argentina claims sovereignty over what it calls the Islas Malvinas and has imposed shipping restrictions.
But UK Defence Minister Bill Rammell said the government had a "legitimate right" to build an oil industry in its waters.
Mr Rammell said the UK would take "whatever steps [were] necessary" to protect the islands and that it had made Argentina "aware of that".
Argentina is already assured of support from President Hugo Chavez of Venezuela, who said Britain was being irrational and had to realise the "time for empires was over".
Nicaraguan President Daniel Ortega has called for "Britain to return the territory of the Malvinas to its real owners - to return it to Argentina" on Venezuelan Telesur television.
Argentina has long claimed the islands. It invaded the Falklands in 1982, before a UK taskforce seized back control in a short war that claimed the lives of 649 Argentine and 255 British service personnel.
But it has ruled out military action and is trying to pressure Britain into negotiations on sovereignty.
Last year Argentina submitted a claim to the United Nations for a vast expanse of ocean, based on research into the extent of the continental shelf, stretching to the Antarctic and including the island chains governed by the UK.
It is due to raise the issue at the UN later this week.
