The 14-member Lima Group said they would not recognize Maduro's hardline socialist government after meeting in the Peruvian capital to discuss ways to step up international pressure on the regime, which has presided over the oil-rich country's economic crisis.
Peru's Foreign Minister Nestor Popolizio said the group had delivered "a strong political message" ahead of Maduro's second-term inauguration on January 10.
"The main message is undoubtedly the non-recognition of the Venezuelan regime's new term," Popolizio told reporters.
The Group, which includes Canada, said Maduro should temporarily transfer power to the National Assembly until free elections can be held.
"Nicolas Maduro is urged not to assume the presidency, to respect the powers of the assembly and to temporarily transfer power until new elections are held," Popolizio said.
Officials said earlier that US Secretary of State Mike Pompeo would participate in the meeting by video conference -- even though Washington is not a member of the 14-nation body.
Pompeo also was to hold bilateral talks with Brazil's new Foreign Minister Ernesto Araujo on the sidelines of the meeting, also by video-conference, according to an agenda released by Araujo's office.
The arrival in power of a new far-right government in Brazil under President Jair Bolsonaro is likely to harden regional opposition to Maduro.
Bolsonaro, who has aligned himself with Washington by expressing hostility towards "authoritarian regimes," said Thursday he was open to discussing his country hosting a US military base "in the future."
Venezuela recently hosted the Russian Air Force, including long-range nuclear bombers, for joint military exercises -- a move that stoked regional tensions.
Cutting diplomatic ties
Peru has previously said it would use the meeting to urge members to cut diplomatic ties with Caracas as Maduro prepares to begin a second term after a controversial May election boycotted by the opposition.
The move coincides with a statement from the Venezuela's opposition-dominated but toothless National Assembly, which said it would not recognize the "illegitimate" Maduro when he takes office.
"We are facing a man who stole an election. We will not have more than a usurper (as president). Neither Venezuelans nor foreigners can recognize Maduro as president," opposition deputy Delsa Solorzano told AFP.
Maduro, who was handpicked by Socialist president Hugo Chavez to succeed him when he died in 2003, was re-elected in May after early elections called by the Constituent Assembly, a body created by Maduro which has in practice replaced the legislature.
The Lima Group statement reiterated its support for the National Assembly, which it recognizes as Venezuela's "constitutionally elected body."
Washington has recently stepped up contacts with South American states dealing with the influx of migrants from Venezuela's worsening economic crisis.
Pompeo was in Cartagena earlier this week for talks with Colombian President Ivan Duque. Both officials have denounced Maduro's "dictatorship" and agreed to step up efforts to isolate his government diplomatically.
"It is very important that the Lima Group has issued this statement to continue exerting pressure with a view to the restoration of democracy in Venezuela," the Peruvian minister said.
The regional group -- created in 2017 after more than 125 people died in anti-Maduro protests in Venezuela -- has refused to recognize the May elections, which were marred by irregularities as well as an opposition boycott.