Havana: Venezuela's leftist, regional allies pledged to support its embattled government at a summit in Havana on Monday, where President Nicolas Maduro accused the opposition of resorting to violence to lay the groundwork for a foreign invasion.

The show of solidarity comes as Maduro faces intensifying criticism abroad, as well as the first sustained wave of anti-government demonstrations in three years, fueled by an economic crisis and erosion of democracy.

"We reject the aggressions and concerted manipulations against our ally," read the statement published by the leftist ALBA bloc of 11 Caribbean and Latin American countries.

The association was founded by Communist-ruled Cuba and its top ally Venezuela 13 years ago as a counterpoint to U.S. influence in Latin America.

It singled out the Washington-based Organization of American States, which has been bitterly critical of Maduro, for what it called attempts to undermine Venezuela's sovereignty.

The OAS chief, Luis Almagro, called for elections to restore full democracy in Venezuela, given the political and institutional crisis roiling the country.

Venezuela's Supreme Court decided in late March to take over the functions of the opposition-led Congress before an outcry forced it to retreat. On Friday, Maduro banned opposition leader Henrique Capriles from political office for 15 years.

"We condemn the interventionist, illegal and pro-imperialist behavior of the OAS secretary general," the statement read.

To preserve Venezuela's independence was to "preserve the independence, unity, and development of the region", said Cuban Foreign Minister Bruno Rodriguez.

"This is the time of unity, peace and hope," said Rodriguez.

Latin America has shifted away from leftist populism toward more centrist policies in recent years and so the ALBA bloc has lost heavyweight regional allies, such as Argentina and Brasil.

Venezuela has come under increased pressure over the past weeks not just from the OAS, but also American and European countries that have condemned its crackdown on the opposition.

During a 1-1/2-hour speech, Maduro said he was open to dialogue but the opposition was not.

"The only way to reach peace is through words, through dialogue," he said. "But the reality is the order has come from Washington for zero dialogue in Venezuela, to make our country explode and give way for a foreign intervention".

Opposition leaders slammed the government for arbitrary use of force in breaking up Monday's demonstrations, pointing to tear gas being fired into one Caracas clinic.