A terminally ill man who is planning to travel to Dignitas in Switzerland to end his life has urged MSPs to change the "cruel, outdated" laws against assisted dying.

Richard Selley, 65, from Perth, will go to the organisation's Zurich clinic in September following a four-year battle with Motor Neurone Disease (MND).

He told STV News he had lost his ability to speak and swallow, using a touch-type computer to communicate, and has also lost most of the power in his arms.

Using the services of Dignitas will cost Mr Selley £10,000, and he said if assisted dying was legal in Scotland it would have "eased many worries".

Holyrood has twice considered Bills to introduce assisted suicide, the first brought forward by independent MSP Margo MacDonald and then, following her death from Parkinson's disease, by Green MSP Patrick Harvie.

They both failed to command a majority in the Scottish Parliament, with Harvie's Assisted Suicide (Scotland) Bill rejected by 36 votes to 82 in 2015.

Mr Selley, formerly head teacher at Loretto junior school in East Lothian, has vowed to spend his remaining time in Scotland trying to persuade MSPs to change the law.

He lives in Perth with his wife Elaine, who is also his carer.

Speaking to STV, he said: "Since my diagnosis with MND four years ago I have tried very hard to remain positive and my palliative care has been outstanding.

"However, as I enter the final stage of my journey, I don't wish to suffer for much longer, so I am seeking an assisted death with Dignitas.

"Despite what some people think, Dignitas do not let people simply fly to Zurich, knock on their door and ask to die.

"I have already had to compose letters, write a life story and obtain medical records that prove that I am terminally ill.

"This has been stressful, particularly as my GP was advised to refuse my request for an up-to-date medical report."

Mr Selley continued: "If I get to Switzerland, I will have to have two interviews with Swiss doctors in order to prove that I am sound of mind and acting of my own free will.

"I will also have to convince Dignitas that I can administer the drug that will end my life.

"As I can no longer swallow, it will need to be done via my feeding tube. I practise the movement required each night."

He told STV that he is fortunate enough he can afford the five-figure sum to visit Dignitas, but added many in similar situations cannot.

But he added: "Having to be fit to fly means that I am choosing to die earlier than I would prefer.

"If an assisted death was possible in Scotland I would be able to die at a time of my choosing at home.

"I wouldn't go ahead with an assisted death if it risked my wife being prosecuted for assisting me in any way.

"For that reason I have to do all the organisation myself. In my condition, that is exhausting."

Mr Selley believes "momentum for a change in the law is growing" but said if that change comes, "it will be too late for me".

In his open letter to MSPs in The Times newspaper, the 65-year-old called the laws against assisted dying in Scotland "cruel, outdated and discriminatory".

He added: "To use Brexit terminology, I wish to leave rather than remain. I don't want to crash out, so I am hoping to negotiate a swift withdrawal agreement...

"If assisted deaths were available in Scotland it would have eased many worries and my remaining time would have been dedicated to my wife, family and friends rather than complex admin."

Gordon MacDonald, chief executive of Care Not Killing, which opposes assisted dying, said: "It is difficult to comment on specific cases without all the details but it is important to realise that no major disability rights organisation or doctors' group supports changing law.

"They know that there is no safe system of assisted suicide and euthanasia anywhere in the world. The safest law is the one we have, which gives blanket prohibition on all assisted suicide and euthanasia.

"It deters exploitation and abuse but at the same time gives some discretion to prosecutors and judges to temper justice with mercy in hard cases."