US preacher and author Anne Graham Lotz has called on supporters to pray after her husband Danny was found unresponsive in a swimming pool at their home in Nort

The 78-year-old was taken to an unnamed hospital for treatment.

Local news reports claim Mr Lotz had suffered diabetic seizures over the past few years but it's unknown whether this event was linked.

Speaking to ABC news, neighbour Jim Rugloski said: "Ambulance has been there a couple times over a couple of years.

"I always keep thinking 'I wonder if Billy Graham is there,' and something, you know."

Writing on Twitter, Mrs Graham Lotz, the daughter of Billy Graham, said: "Danny Lotz is currently in ICU receiving excellent care. The family is standing firm in faith, trusting Jesus. Thank you for your prayers."

Danny Lotz is currently in ICU receiving excellent care. The family is standing firm in faith, trusting Jesus. Thank you for your prayers.

— Anne Graham Lotz (@AGLotz) August 18, 2015

Late on Tuesday night she updated supporters on Facebook suggesting the next 24 hours was important for his recovery.

She said: "Thank you for your prayers as we walk through this valley of the shadow. Danny is holding his own. The next twenty-four hours are critical and should give us some answers. ...

"This I call to mind and therefore I have hope; Because of the Lord's great love we are not consumed, for his compassions never fail. They are new every morning... Lamentations 3:21-23

"God's faithfulness is great. We rest in His love and sovereign will."

The couple have been married almost 50 years and have three children.

Mrs Graham Lotz stepped back from international speaking commitments after last year's Woman to Woman conference hosted by Premier in London to support her husband with his health problems.

Listen to Anne Graham Lotz speaking to Premier last year.