The families of murdered hostages David Haines and Alan Henning have appealed to churches, synagogues and mosques to open their doors to everyone.

They said in a letter that they wanted communities of faith and all people to take part in acts of unity to defeat hatred and celebrate the lives of the two aid workers who were killed by IS militants.

The letter was written by the wife of Mr Henning and the brother of Mr Haines, who said they wrote it because they would "not allow the actions of a few people to undermine the unity of people of all faiths in our society", the BBC reports.

In the letter, they spoke of the families' pride in the two men.

"Their desire to help was not driven by their religion, race or politics but by their humanity. David and Alan were never more alive than when helping to alleviate the suffering of others," they said.

"They gave their lives to this cause and we are incredibly proud of them."

They continued: "Together we have the power to defeat the most hateful acts. Acts of unity from us all will in turn make us stronger and those who wish to divide us weaker.

"We condemn those who seek to drive us apart and spread hatred by attempting to place blame on Muslims or on the Islamic faith for the actions of these terrorists.

"We call on all communities of all faiths in the coming weeks and months to find a single act of unity - one simple gesture, one act, one moment - that draws people together.

"We urge churches, mosques and synagogues to open their doors and welcome people of all faiths and none. All these simple acts of unity will, in their thousands, come together to unite us and celebrate the lives of David and Alan."

A memorial service was taking place in Perth Congregational Church today for Mr Haines, who grew up in the Scottish city.

The service was intended as a celebration of the 44-year-old's life and guests were asked to wear brightly-coloured clothes.

A memorial service for Mr Henning was held last week and attended by hundreds.