HAVANA: The US and Cuba are close to a deal on restoring regularly scheduled commercial flights, Cuban and American officials said.

The diplomatic advance would help open the way for US airlines to begin flying to Cuba within months in what would likely be the biggest step toward tighter economic ties since the two countries began normalizing relations last year.

Officials on both sides said they had reached an understanding on key points and hoped to reach a formal deal within hours or days.

Teams who have been meeting since Monday in Washington “have made important advances in negotiating a memorandum of understanding on establishing regular flights between Cuba and the US, and shortly they will be ready to announce a preliminary agreement on this issue,” said Josefina Vidal, head of North American affairs for Cuba’s foreign ministry.

US State Department spokeswoman Kerry Humphrey said that the countries “are making progress but still negotiating.”

Right now, American and Cuban travelers must fly on charter flights that are expensive and difficult to book, forcing travelers to buy paper tickets in Cuba or e-mail documents and payment information back and forth with an agent in the US. Those flying often must arrive at the airport four hours in advance and pay high prices for baggage in excess of strict weight limits. US officials and aviation executives have speculated that Cuba could allow more than a dozen flights to and from the US a day.