Venezuelan President Nicolas Maduro called for a meeting of South American leaders over the growing turmoil facing his country, where the death toll from a month of anti-government protests hit 20.
The under-pressure leader's move on Thursday came a day after he broke off relations with Panama, following its call for the Washington-based Organisation of American States to convene on the crisis.
Maduro's government later ordered Panama's ambassador, Pedro Pereira, and three other diplomats working at the mission to leave the country within 48 hours, Panamamian Deputy Foreign Minister Mayra Arosemena said. Arosemena insisted that despite the measures against the diplomats, Panama "has every intention of maintaining the best relations with Venezuela".
In Washington, the OAS Permanent Council was meeting to discuss a draft resolution calling for dialogue and condemning violence in Venezuela, as well as Panama's proposal for foreign ministers to hold crisis talks.
Street protests erupted in Venezuela on February 4 and have continued every day since in the biggest challenge yet to Maduro's nearly year-old socialist government.
Public anger over rampant crime, shortages of basic goods and arrests of protesters have fuelled the unrest, which the Venezuelan leader insists is part of a US-backed plot by "fascists" to destabilise his authority.
Protesters have accused government forces of committing human rights abuses.