Brian O'Callaghan-Westropp was last seen on Monday

Fears are rising for an Irish man who's missing in Greece where wildfires have killed at least 76 people - his wife is in hospital with burns.

Newlywed Brian O'Callaghan-Westropp and Zoe Holohan married last week before flying out to Greece on their honeymoon.

It's understood the pair got separated while trying to escape the flames in the seaside resort of Mati on Monday.

Brian O'Callaghan-Westropp and Zoe Holohan | Image: Facebook

The Department of Foreign Affairs has confirmed it's offering consular assistance to a number of Irish citizens in Greece. 

Dozens of homes and buildings have also been destroyed as a result of the fires, and people have been forced to flee their homes in some affected areas.

Three days of national mourning are beginning there.

People stand amid the charred remains of burned-out cars in Mati east of Athens | Image: Aristidis Vafeiadakis/Zuma Press/PA Images

Greek Prime Minister Alexis Tsipras has described the fire as an 'unspeakable tragedy'.

"Today Greece is mourning, and in memory of those who are lost we are declaring a three-day period of national mourning.

"But we must not let the mourning overwhelm us - because these hours are hours of battle, unity, courage and above all solidarity".