Human remains, believed to be of a man wanted on suspicion of murdering his three daughters, aged nine, eight, and five, have been found in the US state of Washington.

Police had been searching for Travis Decker since officers found his phone and the bodies of his girls Paityn, Evelyn, and Olivia in a remote campground on June 2. His truck was also found nearby.

While positive identification has not yet been confirmed, preliminary findings suggest the remains belong to Travis Decker, Chelan County Sheriff's Office said in a statement.

The remains were discovered in a remote wooded area south of the town of Leavenworth, in Washington state, officials said.

Decker, 32, was wanted on kidnapping and first-degree murder charges, according to Washington's Wenatchee Police Department, and officials believed he had been hiding in a remote part of the mountainous and wooded state.

The girls' mother reported them missing on May 30 after Decker failed to return his daughters to her home in Wenatchee, Washington, following a visit. He also did not take her phone calls.

They died from apparent suffocation, and their wrists had been bound with zip ties, authorities said, according to the BBC's US partner CBS News.

Decker was an ex-soldier and may have gone to mountain survival school as part of his military training, officials said.

It sounds like at times he would go out and would be off-grid for sometimes up to two and a half months, Sheriff Morrison said after speaking to Decker's family.

The remains were found on Thursday on Grindstone Mountain, a few miles from where Decker's daughters' bodies were found in June, reports CBS' local news partner KIRO-TV.

A $20,000 (£14,812) reward had been announced by the US Marshals Service for information leading to Decker's capture.

The search had caused widespread closures of national forests popular among hikers in the area.