The abortive attempt by Manuel Zelaya, the Honduran President bundled out of the country in his pyjamas in a military coup last week, to fly back to Tegucigalpa has raised tensions in the impoverished central American state.

Thousands of his supporters gathered at the airfield on Sunday but were confronted by armed troops who opened fire, killing two people. And as President Zelaya, his arrival blocked by military vehicles parked on the runway, diverted to El Salvador, international pressure on the coup leaders increased.

The United Nations Secretary-General again called the coup unacceptable. Venezuela announced a cut-off of all oil shipments. European Union members prepared to withdraw ambassadors. And the Organisation of American States (OAS), which suspended Honduran membership, cut off aid and favourable trade arrangements. So too did the World Bank.

Despite this overwhelming outside pressure the coup members remained defiant. They insisted that they had acted only to protect the constitution after President Zelaya had planned an illegal referendum on his plans to stand again for election in November. They said that they would not be bullied into action nor back down in face of pro-Zelaya demonstrations.

The question is: can Roberto Micheletti, the interim President, hold out until November? His country cannot endure a cut-off of oil and a trade embargo for long. He has been unable to persuade Washington to open talks on Honduras’s future. And he has found that the coup united both left-wing and right-wing governments in Latin America in condemnation.

The coup had widespread support, though, and it will be difficult for Mr Micheletti to find a face-saving retreat. He has already announced that the ousted President would be arrested on 18 alleged criminal charges, including treason and failing to implement more than 80 laws approved by the Honduran Congress.

Mr Micheletti withdrew from the OAS only hours before Honduras was due to be expelled and faces the united opposition of presidents from Venezuela and Colombia, as well as those of Argentina and Ecuador who had intended to accompany President Zelaya on his return — until they realised the danger to his chartered plane.

Mr Zelaya has played his cards skilfully since being exiled. He swiftly announced that he would not seek re-election. He then appealed to Latin America to condemn the coup because it threatened to bring back the bad old days of junta rule in much of the continent. And he made sure that he received the public backing of not only Washington but of key nations in Europe such as Spain and France.

The coup leaders probably underestimated Mr Zelaya’s support among the poor and rural voters after his political lurch to the Left. The interim Government has extended the curfew to stop people gathering in the early evening, but that has not prevented many from announcing further protests.

The shooting of two demonstrators on Sunday will only harden their resolve and may lead to wavering among the troops being ordered to enforce the curfew.

Honduras now needs a face-saving way to re-admit Mr Zelaya, but he is determined to go back on his own terms and at a time of his choosing. His anger at his ousting and his determination to protect his record make him unlikely to accept any compromise. Those who will suffer will be his own countrymen, who will soon find the international boycott beginning to bite.

Much of the outside backing for Mr Zelaya is opportunistic. Venezuela is clearly trying to pose as a champion of democracy.

Other countries are eager to show that they have turned their backs on their own history of military governments. And the Obama Administration is loath to take sides, not wanting to be seen to intervene against a left-wing President, as it has in the past, or to dictate what should happen in the Western hemisphere.

Mr Zelaya had a poor record in office. Crime and corruption were on the rise, populism was used in an attempt to gain the support of the trade unions and left-wing social movements, and his defiance of the country’s highest court was scarcely democratic.

That counts as little, though, compared with the opposition throughout Latin America to military coups. For, in truth, if the coup succeeds in Honduras few democratically leaders will feel safe. Generals who have remained in their barracks for 20 years might begin to wonder whether they too could oust unpopular governments and make moves on the presidential palace.

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