Image copyright Getty Images Image caption American jets are almost certain to become a more regular sight at Havana's Jose Marti International Airport

The United States and Cuba have agreed to restore regular commercial flights, in a deal that could jumpstart economic relations between the two countries.

The agreement paves the way for thousands of visitors to the island on a daily basis.

The deal was announced on Thursday, exactly one year since President Barack Obama and President Raul Castro announced a historic detente.

It is not known when the first Cuba-bound flights will take off.

The pact - the most significant business development since the presidents' announcement one year ago - allows US airlines to negotiate with the Cuban government over commercial flight routes and schedules.

It could mean more than a dozen flights arriving into Cuba from the US a day, officials said.

Image copyright Getty Images Image caption Before the deal, only chartered flights could fly people between the US and Cuba

The understanding is a key development as Cuba and the US continue to negotiate over a number of issues which could ultimately see the US trade embargo lifted.

The news comes as travel between the US and Cuba surged by over 70% this year, according to Reuters.

Thousands of Americans are already visiting the island and hotels and hostels are booked for months.

But those travelling have to do so using difficult-to-book charter flights or via third countries, and are forced to navigate an intricate web of laws in order for their travel to be legal.

The State Department reminded US citizens on Thursday that a ban on touristic travel to Cuba remains in place.

A significant step - Will Grant, BBC News, Havana

Media playback is unsupported on your device Media caption It has been a year since Cuba and the US started to normalise relations

In some regards, the move to restore commercial flights is one of the most significant steps of the past 12 months in that it will further facilitate the arrival of American visitors to Cuba.

With tourism increasingly becoming the main economic motor for the communist-run island, it comes as little surprise that the Cuban government was as keen on this particular measure as their counterparts in Washington.

It has been an extraordinary year in Cuba-US relations. But sticking points remain in normalising the bilateral ties.

In particular, the Cubans want to see the US economic embargo on the island lifted as soon as possible, something President Obama has repeatedly urged Congress to do.

Messrs Castro and Obama announced the normalisation of relations on 17 December 2014, after more than 50 years of hostility between the Cold War foes.

One year out, President Obama is marking the anniversary by calling on the US Congress to lift the trade embargo on Cuba, releasing a statement that says, in part: "Congress can support a better life for the Cuban people by lifting an embargo that is a legacy of a failed policy".

Since then, embassies have opened in Havana and Washington, a pilot postal programme has been agreed, phone links established, environmental deals have been inked, human rights talks have started, as well as a number of other developments.

Yet much stands in the way of fully-restored relations, most notably the US-imposed trade embargo, which Republicans have strongly defended.