Paraguay's new government battled a wave of criticism on Sunday as several of the country's closest allies condemned the dismissal of President Fernando Lugo by legislators, some calling it a congressional coup.

Venezuelan President Hugo Chavez said his government will cut off fuel sales to the poor South American country. Venezuela had become a key supplier to Paraguay as Chavez had built close ties with Lugo, a moderate progressive.

Former vice-president Federico Franco, who was sworn in as president following Lugo's ouster on Friday, said newly appointed Foreign Minister Jose Felix Fernandez would represent Paraguay at a summit of the regional trade bloc Mercosur that starts Monday in Mendoza, Argentina, with heads of state gathering there on Thursday.

"He will take charge of seeking to solve the discrepancies with countries that are our neighbours and friends," Franco said after attending Sunday mass.

That could set up an international showdown, since Lugo also said he plans to attend the summit. Appearing early Sunday, he denounced his ouster — accomplished by congressional impeachment — as a "parliamentary coup" and a "foreordained sentence" that wasn't based on proper evidence.

All three other Mercosur members reacted with alarm to Lugo's removal, and the fact that Lugo's impeachment trial in Paraguay's Senate lasted just five hours on Friday — giving the president little time to mount a defence. Brazil and Argentina announced they were calling their ambassadors home and Uruguay also expressed concern.

Chavez said Venezuela also was pulling out its ambassador and that it would not recognize the new government.

His decision to cut oil shipments could hurt Paraguay, which has received increasing quantities of Venezuelan oil since 2004. Paraguay currently owes Venezuela's state oil company Petroleos de Venezuela SA nearly $300 million, out of about $400 million in total debts to oil suppliers.

5 impeachment charges

Lugo was elected four years ago, ending 61 years of rule by the conservative Colorado party, on promises of agrarian reform to help the country's many poor and landless people, but his allies increasingly turned against him in recent years.

He was tried for impeachment on five accusations, including that he improperly allowed political parties to hold a meeting in an army base in 2009; that he allowed about 3,000 squatters to illegally invade a large Brazilian-owned soybean farm; that his government failed to capture members of a guerrilla group, and that he signed an international protocol without properly submitting it to Congress for approval. The central charge related to a deadly clash between police and landless protesters earlier this month on a remote forest reserve.

Lugo said his truncated presidency was targeted because he tried to help the South American nation's poor majority. Asked whether he had any hope of retaking office, Lugo exhorted his followers to remain peaceful but suggested that national and international clamour could lead Paraguayan legislators to reverse his impeachment.

"In politics, anything is possible," Lugo said.

Franco is to serve out the rest of Lugo's term, which ends in August 2013. His administration has been recognized by the rightist governments of Germany, Canada and Spain.