AN INCREASINGLY anxious UK government is closely monitoring a build-up of Argentinian military strength and a series of confrontations with the RAF close to the Falkland Islands, Scotland on Sunday can reveal.
The activity has led Tony Blair's most senior advisers to demand he issues a "hands-off" warning to Buenos Aires.
Downing Street is facing growing fears for the future of the islands - which were seized back from Argentinian control in a bloody and symbolic campaign ordered by Margaret Thatcher almost a quarter of a century ago.
High-ranking officials in both the Ministry of Defence and the Foreign Office have confessed to concerns that the changing political situation in Argentina and Latin America, as well as Britain's growing military commitments around the world, are conspiring to undermine the security of the Falklands.
The sense of threat surrounding the Malvinas islands, regained from the Argentinian military junta in 1982, has been gathering for several months as President Nestor Kirchner's government has presided over an unprecedented revival in the strength of its air force - now at twice the strength it was during the 1982 conflict.
Several planes are believed to have overflown island airspace in a bid to test RAF defences. A number of Falkland vessels have been seized in waters close to Argentina.
The already tense situation has been further exacerbated by the Venezuelan president Hugo Chavez, a Kirchner ally, who responded to criticism from Blair this month by telling him to "return the Malvinas to Argentina".
Scotland on Sunday understands that the British government still hopes to reinforce the peaceful relations between the two nations with "a diplomatic offensive", including a series of gestures of reconciliation in the run-up to the 25th anniversary of the conflict next year.
HMS Endurance became the first Royal Navy ship to visit an Argentinian port since the conflict last month, when it arrived in Ushuaia to participate in a ceremony commemorating those killed on both sides during the conflict.
But many Argentinian veterans opposed the move, and a Foreign Office source last night conceded that Tony Blair now faced having to reinforce Britain's commitment to the islands - perhaps by sending more troops to the South Atlantic.
"There have been a number of incidents, and even if they weren't all connected, they might suggest that the government in Buenos Aires is feeling a bit bullish," the source said. "No one is saying they are about to invade but you have to maintain your position. We all remember that, after the original conflict, Britain was accused of giving the junta the impression that their invasion would not be opposed.
"We would, of course, prefer them to get the message, but maybe - sometimes - we just have to underline it ourselves."
The British military presence in the South Atlantic has dropped from 1,900 troops in 1998 to 1,200 now, while 8,000 troops are deployed in Iraq and 3,000 are heading for Afghanistan. The Falklands garrison is dwarfed by the 20,000-strong British presence in Germany, the 10,000 in Northern Ireland and even 3,400 in Cyprus.
But critics warn that the garrison, which costs more than 110m a year, is hopelessly inadequate for fending off any renewed threat from abroad.
Defence experts and staff within the MoD have become concerned about the increase in military activity under Kirchner, and about his political allegiances - particularly with the controversial Chavez.
In recent years, the Argentinian air force has doubled in size, and is now the largest in South America. A major upgrade has fitted new missiles to Mirage fighters and Pucara ground-attack planes.
The British government believes that increased military flights have probed RAF radar defences in the Falklands to assess the time taken by Quick Reaction Alert Tornadoes to reach the area.
The activity is matched in the disputed local sea-space, where each side operates a 200-mile exclusion zone around its coast. A British patrol found an Argentine submarine off the waters of South Georgia, while Argentina's coastguard last week captured a Falklands-flagged fishing vessel it claimed was operating in the country's "economic exclusion zone". The vessel, John Cheek, and its 31-strong crew were taken to the port of Comodoro Rivadavia, 945 miles south of Buenos Aires, where they faced the prospect of heavy fines or having their catches seized.
The vulnerability of British outposts around the world has been underlined by the increased commitments of UK military forces in trouble spots including Iraq and Afghanistan. A number of critics in London and the Falklands believe that the Argentinians may take advantage of the "overstretch" to cause trouble in the south Atlantic.
A senior Ministry of Defence source said: "This could be termed as sabre-rattling, but when our forces are deployed in so many locations, its potential for causing mischief is magnified. We've been watching a steady build-up of the Argentine air force over the past year. Frankly, they have no need for such a large fighting force, and there is concern in Whitehall as to what this is all about."
He added: "The Argentine air force is at least twice the size of that we fought during the Falklands War and the question has to be asked: how many more aircraft do they need?"
Tory MP Andrew Rosindell, chairman of the all-party Falkland Islands Group, said: "It is time the British government told the Argentinians they won't get away with this alarming hostility. I hope the Argentine government is not planning any military action, but we have got to learn the lessons of the past and any actions have to be rebutted. The moment we are seen to be weakening, our resolve is going to be questioned."
Rosindell said residents' fears of abandonment were reinforced last week when the BBC announced it was cutting its twice-weekly bulletins to the islands.
Dr Francisco Panizza, senior lecturer in Latin American politics at the London School of Economics, said the signs of a new power base around Chavez had sparked anxiety among Western governments.
"Kirchner's leadership is characterised by his populism, defining Argentina against her enemies," he said.
"He has used multinationals and oil companies, so referring to the Malvinas would fit in with that - but I don't think he is in a position to invade the islands again."
Panizza added that the Venezuelan leader's intervention "would have resonated very well in Buenos Aires".