Rebel armoured personnel carrier heads towards Congress

Mr Oviedo is now believed to have returned to Paraguay, and last month police embarked on a fruitless search of an apartment block in the country's second city, Ciudad del Este, after reports that he had been visiting his brother there.

The rebels who staged the latest coup attempt said they belonged to a previously unknown movement named after Fulgencio Yegros - an army captain who played a key role in the 19th-century fight for Paraguayan independence - but there is little doubt that they were followers of Mr Oviedo.

Paraguay is frequently gripped by rumours of coup plots, but in this case the outbreak of violence took seasoned observers by surprise.

This latest resort to military force is being seen as a last desperate attempt by Mr Oviedo to seize power in Paraguay, in the wake of recent mass protests by peasants and trade union leaders who oppose the economic policies of President Luis Gonzalez Macchi.

Political uncertainty

Mr Macchi belongs to the Colorado Party, whose grip on the levers of power dates back to the authoritarian rule of General Alfredo Stroessner.

As an attempt to resolve the political crisis that followed Mr Arga�a's assassination, Paraguay was supposed to have a government of national unity including members of the opposition, but the Colorados soon quarrelled with the other parties, most of whom have now pulled out.

There is a widespread feeling in Paraguay that the Colorados' offer to share power was a sham from the start. Mr Macchi was never a strong political leader, and his government has been weakened by the defections.

Mr Oviedo appears to have been seeking to exploit the political uncertainty.

He may have thought that the prospect of another military strongman in power would appeal to ordinary Paraguayans - but his gamble has failed to pay off.