The United States broke a longstanding diplomatic taboo by holding secret talks with Hamas on securing the release of US hostages held in Gaza, sources tell Reuters.

US hostage affairs envoy Adam Boehler has the authority to talk directly with Hamas, the White House said when asked about the discussions, which broke with a decades-old policy against negotiating with groups that the US brands as terrorist organisations.

Boehler and Hamas officials met in Doha in recent weeks, two sources briefed on the negotiations said. It was not clear who represented Hamas.