Mexico said on Friday that it is willing to mediate between the government of Venezuelan President Nicolas Maduro and opposition leader and congress chief Juan Guaido, if both sides request and agree to it.
Venezuelan Defense Minister Vladimir Padrino Lopez said that the armed forces do not recognize Guaido as interim president.
Canada, the U.S., Brazil, Germany and other countries have recognized Guaido as Venezuela's president. If Maduro remains in power, the security of the remaining US diplomats is uncertain.
Maduro has also shuttered USA missions in the United States.
"They believe they have a colonial hold in Venezuela, where they decide what they want to do", Mr Maduro said in an address broadcast live on state TV. "Mike Pompeo beat me to it. Thanks Mike", said Maduro ironically, adding that Jorge Arreaza has his "visa" to go to NY.
In response, Russian Foreign Minister Sergei Ryabkov said: "We warn against that".
"Thanks, Mike... We're going to tell the truth about the articles of the constitution, about the coup".
A Reuters witness at around 8:30 a.m. local time (1230 GMT) saw a convoy of sport utility vehicles accompanied by police motorcycles and vehicles with flashing lights drive onto a Caracas highway in the direction of the airport.
FILE - Canadian Foreign Minister Chrystia Freeland takes part in a news conference at the Embassy of Canada in Washington, U.S., August 31, 2018.
Many transit Colombia on their way to Peru or Ecuador, she said, adding: "We have seen a significant number in dire need of global refugee protection and humanitarian assistance".
Russia's Defence Ministry and Venezuela's Information Ministry did not respond to requests for comment about the contractors.
Petra Kvitova: Tennis star in tears over Barty win after knife attack
Barty had said she was "all good" and had no concerns following her third-round win over Maria Sakkari on Friday. "Thank you guys. Kvitova will start this match as the favourite to win - this is a given. "Looking forward to the next match".
United Nations human rights boss Michelle Bachelet called on Friday for an investigation into alleged excessive use of force by Venezuelan security forces against protesters, adding that she was "extremely concerned" that the situation could rapidly spiral out of control.
Counter protests also have been organized by the Venezuelan government, which has accused the opposition of provoking violence.
Guaido, who has galvanized Venezuela's opposition, proclaimed himself interim president on Wednesday during a march of hundreds of thousands in Caracas.
One of the two anonymous Russian sources, who is close to the Wagner group and fought in foreign conflicts where it was active, said the contractors first arrived in advance of the May 2018 presidential election, but another group arrived "recently". Guaido has promised future amnesties to military members if they disavow Maduro.
Guaido took the helm of the National Assembly on January 5 with a call for the armed forces to recognize Maduro as a "usurper" after his May 2018 re-election, widely viewed as fraudulent.
Guaido declared himself interim president on Wednesday.
Though many rank-and-file troops suffer the same hardships as countless other Venezuelans when it comes to meeting basic needs like feeding their families, Maduro has worked to cement their support with bonuses and other special benefits.
The government and opposition held talks that fell apart previous year, with the opposition saying they would only agree to an accord allowing a fair election.
Maduro warned off any attempt to take control of Citgo, the country's primary offshore asset.
The United Nations human rights boss Michelle Bachelet called on Friday for an independent investigation into alleged excessive use of force by Venezuelan security forces or allied militia, citing reports of at least 20 people killed this week.
Speaking at the World Youth Day in Panama, Pope Francis's spokesman said he was "praying for the victims and for all the people of Venezuela".