Donald Trump has suggested that Venezuela’s leader Nicolás Maduro could be easily toppled by a military coup as the US stepped up financial pressure with fresh sanctions on Maduro’s inner circle.

Trump declined to respond to questions about whether a US-led military intervention in the crisis-stricken country was possible, but on the sidelines of the UN general assembly he said: “It’s a regime that, frankly, could be toppled very quickly by the military if the military decides to do that.

“It’s a truly bad place in the world today.”

His comments came after the US slapped financial sanctions on Maduro’s wife, vice-president and other senior Venezuelan figures.

As part of the actions, the US barred Americans from doing business with and will seize any financial assets in the US belonging to the first lady, Cilia Flores, Vice-President Delcy Rodríguez, the communications minister, Jorge Rodríguez, and defence minister, Vladimir Padrino.

“We are continuing to designate loyalists who enable Maduro to solidify his hold on the military and the government while the Venezuelan people suffer,” the treasury secretary, Steven Mnuchin, said in a statement. “Treasury will continue to impose a financial toll on those responsible for Venezuela’s tragic decline, and the networks and frontmen they use to mask their illicit wealth.”

During his speech at the United Nations general assembly, the US president singled out Venezuela for criticism, saying: “Not long ago, Venezuela was one of the richest countries on Earth. Today, socialism has bankrupted the oil-rich nation and driven its people into abject poverty …

“We ask the nations gathered here to join us in calling for the restoration of democracy in Venezuela.”

Over the past two years the Trump administration has sanctioned dozens of individuals, including Maduro himself, on allegations of corruption, drug trafficking and human rights abuses.

But until now it had spared key leaders such as Delcy Rodríguez, as well as the US-trained Padrino, believing they occupy seats of power and could play a key role in an eventual transition.

David Smilde, a Tulane University professor who has spent more than two decades living and working in Venezuela, said Tuesday’s actions would seem to suggest the US has given up trying to sow division within the government in the hopes it could force a democratic transition from within.

“This clearly breaks from that strategy,” said Smilde. “If everyone is sanctioned then it could end up uniting the government.”

Trump, arriving at the United Nations general assembly before his speech Tuesday, said Venezuela is “a very sad case and we want to see it fixed. What’s happening there is a human tragedy.”

But beyond rallying Maduro’s opponents, it is unclear what impact the sanctions will have.

For more than a year, top US officials have struggled to build support for more sweeping oil sanctions, facing resistance from energy companies still active in the country and fearing it could tip the Opec nation over the edge at a time of hyperinflation and widespread food and medicine shortages.

As part of the actions announced on Tuesday, the US Department of the Treasury also seized a $20m private jet belonging to an alleged frontman for powerful socialist party boss Diosdado Cabello.