Joint talks among the United States, Cuba, and Mexico to fix the maritime boundaries of the three countries in the Gulf of Mexico are likely to be complex and stretch beyond 2018, a senior Mexican official said on Wednesday.

The United States said earlier in the day the nations would begin discussing the boundaries as part of President Barack Obama's plan to restore diplomatic relations with Cuba.

Negotiations on maritime boundaries could have implications for deep water oil and gas development in the Gulf of Mexico, which for decades has been dominated by the US.

Sergio Alcocer, the Mexican deputy foreign minister responsible for North America, said the process of assessing the value and distribution of resources in the oil and gas-rich Gulf of Mexico was complex and likely to last several years.

"We three countries are the owners of the Gulf of Mexico, and the key thing is to reach an agreement and establish the rules under which we can exploit these resources in a sustainable way," Alcocer said.

The United States and Cuba have delimited maritime space between the two nations within 200 nautical miles from shore, and Mexico has its own bilateral accords with the two.

But the three countries have continental shelf in an area within the Gulf of Mexico where no boundaries are yet fixed.

While the oil deposits Mexico is looking to exploit are far from Cuba, Alcocer said natural gas deposits closer to the island could be a central issue in talks.

Alcocer said he thought it was unlikely the talks would conclude under Mexican President Enrique Pena Nieto, who is due to leave office at the end of November 2018.

No start date was yet set for the talks, he added.