The parents of a Canadian citizen and his American wife who were kidnapped nearly five year ago in Afghanistan have appealed to the Afghan Taliban and the Haqqani network to release the couple and their two children on humanitarian grounds

Patrick Boyle and his wife Linda, recorded a video message in English with Urdu and Pashto sub-titles to launch the appeal in the hope that their eldest son, Joshua Boyle and his wife Caitlan and their two children born in captivity would be finally freed.

Joshua Boyle, 33, and his wife Caitlan Coleman, 31, were kidnapped from the Wardak-Kabul road in October 2012.

The couple set off in the summer of 2012 from their home in Perth-Andover, N.B., for a journey that took them to Russia, the central Asian countries of Kazakhstan, Tajikistan and Kyrgyzstan, and then to Afghanistan.

Later, it emerged that the couple was in the custody of the Haqqani network, which is part of the Afghan Taliban movement and is headed by Sirajuddin Haqqani.

In recent years, Haqqani has also operated as the deputy leader of the Afghan Taliban group.

A few videos of the kidnapped couple and their two sons, both born in captivity, have also been released as a means to put pressure on the families of Joshua Boyle and Caitlan Coleman and the governments of Canada and the US to accept the Haqqani network’s demands in return for their release.

Though the demands weren't made public, these have been conveyed to the families and the Canadian and American governments through intermediaries.

The Haqqani network earlier demanded release of their 10 prisoners, all held in Afghanistan, but it was learnt the list has been reduced to eight.

Three of these prisoners are very important for the Haqqani network. One is Anas Haqqani, the brother of Sirajuddin Haqqani and son of noted Afghan mujahideen commander Maulvi Jalaluddin Haqqani, who was arrested by US officials in Bahrain after returning from a visit to Qatar and handed over to the Afghan government.

He has later sentenced to death by an Afghan court, but President Ashraf Ghani's government hasn't executed him yet despite demands by certain political groups in Afghanistan. The other precious prisoner for the Haqqani network is Qari Rasheed, who had accompanied Anas Haqqani on the trip to Qatar and was arrested by the Americans in Bahrain. The third prisoner is Haji Mali Khan, a maternal uncle of Sirajuddin Haqqani.

In their appeal, Patrick Boyle and Linda mentioned the case of Sirajuddin Haqqani's brother Anas Haqqani without naming him. "Our family was asked very clearly to do everything that it could to influence change and overturn Afghanistan's policy, to stop the execution of your brothers. We have done the best an ordinary Canadian family can do. I have personally written to several of the most senior government officials in Afghanistan - those with great power over any execution of your brothers.

These letters were well received," argued Patrick Boyle. He said they also pushed hard on the Canadian and US governments to encourage Afghanistan not to uphold or approve the death sentences.

 In the video appeal, Patrick Boyle is heard saying to the Haqqani network leadership: "While we are a modest family, our efforts have resulted in some success. Your family members are still alive. The death sentence has not been upheld and has not been carried out. You know this to be true."

The appeal says: "We are now respectfully asking you to show mercy to our family members in return. They are a young family of innocent civilians. They have never had any government or military ties. The Islamic Emirate of Afghanistan can follow the tradition of other governments of Muslim nations and release prisoners at Eid as acts of kindness, charity and mercy in the spirit of Ramadan."

The appeal are addressed to the Taliban supreme leader Mulla Haibatullah Akhundzada and Sirajuddin Haqqani and they are asked to show mercy on their family. At one point, the appeal says: "We recognize the many wrongs suffered by the people of Afghanistan. Holding our family members will not remedy those wrongs."

Patrick Boyle and Linda also spoke in the video to their son and daughter-in-law, praising their strength and asking them not to despair and don't give up.