CARACAS, Venezuela — Tempers flared at airline offices in Caracas on Friday as Venezuelans reacted angrily to international carriers’ refusal to sell tickets after the government devalued the bolívar, the local currency, for flights abroad.

The offices of American Airlines, Delta Air Lines, United Airlines and Panama’s Copa Airlines were all either closed or halted sales for several hours as the new exchange rate took effect, adding to uncertainty as carriers try to collect $3.3 billion they say they’re owed by the socialist government.

“Don’t waste your time,” a United representative, sticking her head out from behind a closed glass door, told 10 customers standing outside a ticket office at Caracas’ Centro Lido shopping mall. “It’s out of our hands. We can’t sell any more tickets.”

When customers protested they would never experience such poor service in the U.S., the agent, said: “Our situation is different than the U.S.,” and closed the door.

Megan McCarthy, a spokeswoman for United in Chicago, said the airline continues to sell tickets in Venezuela but acknowledged that ticket sales had been halted for a few hours as prices in its system were adjusted.

United has a single daily flight between Houston and Caracas. “When the exchange rate was updated, we had to hold selling them,” she said, adding that its ticket office in Centro Lido would reopen Saturday.

For the past few months, many airlines have been locked in a battle with President Nicolás Maduro’s cash-strapped government to repatriate $3.3 billion that it says is trapped inside the country by rigid currency controls. The situation worsened this week when the government said revenue from ticket sales in bolívares would now be converted at a new exchange rate.

Weeks of closed-door meetings have failed to produce a deal, with airlines balking at the government’s offer to honor the debt.

In the meantime, the travel plans of millions of Venezuelans are in doubt amid fears that more airlines could follow the example of Ecuador’s TAME airline, which this week said it was suspending its daily flights to Venezuela until the government pays it $43 million it says it is owed for ticket sales in the country.