Dutch Jesuit priest Father Frans van der Lugt has allegedly been shot dead in the besieged Syrian city of Homs by a masked gunman.

Van Der Lugt, 72, lived in Syria for decades and had played a key role in publicising the plight of the people of Homs - Christians and Muslims alike.

Homs-based priest Assad Nayyef and the London-based Syrian Observatory for Human Rights said the gunman first beat the Roman Catholic priest, then shot him dead with two bullets to the head.

The Jesuit died instantly.

"I can confirm that he's been killed," Jan Stuyt, secretary of the Dutch Jesuit Order, told AFP by phone.

"A man came into his house, took him outside and shot him twice in the head. In the street in front of his house."

He said he was not aware of particular threats to van der Lugt. The priest will be bured in Syria "according to his wishes", Stuyt added.

A trained psychotherapist, Van Der Lugt had been living in the Middle East since 1966. In the 1980s he set up an agricultural project outside Homs where young people with mental health problems could find employment.

While many Christians were leaving the city after the rebels moved in, the priest chose to stay, claiming "I am the shepherd of my flock".

During the three-year-long civil war, the priest repeatedly refused to leave the monastery in the city's Bustan al-Diwan neighbourhood, a rebel stronghold which had been besieged by forces loyal to Syrian president Bashar al-Assad.

In February 2014, while an operation to allow access to humanitarian aid was ongoing, van der Lugt said in a video (in Arabic):

Christians and Muslims are going through a difficult and painful time and we are faced with many problems. The greatest of these is hunger. People have nothing to eat. There is nothing more painful than watching mothers searching for food for children in the streets...I will not accept that we die of hunger. I do not accept that we drown in a sea of hunger, letting the waves of death drag us under. We love life, we want to live. And we do not want to sink in a sea of pain and suffering.

A thriving commercial city before the war, Homs degenerated into a district brutalized by war and starvation as it was blocked by Syrian government troops.

The priest said the Old City used to be home to 60,000 Christians with 10 churches in the besieged area. "Now I find myself alone with only 66 other Christians," he told the Telegraph.

Van der Lugt stayed in Homs even as 1,400 people were evacuated during a UN-supervised operation that started on 7 February and also saw limited supplies of food brought into the city.