MADRID, May 7 (Reuters) - Spanish energy firm Naturgy said on Tuesday that its supply contracts with Algeria do not include any clauses that would be affected by changes in the shareholding structure.

The comments come after a source told Reuters that Algeria would cancel deliveries of gas to Naturgy if the Spanish firm's shares are sold to another company.

"There have never been any clauses in the supply contracts that were affected by possible changes in the shareholding of either party," a spokesperson told Reuters.

"In fact, such shareholder changes have occurred in the past and have had no impact on the contracts' performance," he added.

Naturgy has key gas contracts with Algerian state oil and gas company Sonatrach for about 5 billion cubic metres (bcm) per year, according to the latest information reported by the company to the markets in 2022. The parties are negotiating prices for 2023, retroactively, and 2024.

Algerian gas made up roughly one-third of Spain's total gas imports in the first three months of the year, according to data from Spanish gas grid operator Enagas.

The bulk of the supply comes via the Medgaz pipeline, in which Naturgy is a minority partner and Sonatrach holds a 51% stake. Sonatrach also has a stake of about 4% in Naturgy. (Reporting by Pietro Lombardi; Editing by David Latona)