Portuguese officials have said there is no evidence to support reports that a fire-fighting plane has crashed amid a battle to contain huge wildfires.

None of the specialist water-carrying planes involved in the effort are missing, a spokesman for the Civil Protection Agency (CPA) has said, in comments that suggest initial reports of a crash were false.

It comes after an official with Portugal's Air Accident Office said they were aware of a reported crash of one of the planes helping to tackle fires that have killed more than 60 people in central Portugal.

The reports of the alleged accident were said to have originated with the CPA - but a spokesman said they had never raised an alarm.

A public radio station quoted local woman who said she saw a plane downed in a fireball.

The CPA said that an abandoned caravan containing gas bottles had exploded in the area, and may have misled people into thinking there was a crash.

Spokesman Fausto Coutinho said: "it could have been a strange coincidence, with a plane passing over and an explosion occurring on the ground at the same time."

More than 1,000 firefighters have been battling the blaze in Pedrogao Grande. They believe they are close bringing it under control after three days.

Portugal's prime minister Antonio Costahas has declared three days of national mourning for those killed in the fire, which he described as "the biggest tragedy" the country has experienced in years.

Investigators believe the blaze was sparked by a lightening strike during a "dry thunderstorm" on parched ground.

Temperatures had reached 40C in the area, about 95 miles north-east of the capital Lisbon, in recent days.

Dry thunderstorms occur in high temperatures when falling water evaporates before reaching the ground.