Jafar and his wife Naseem wave goodbye to well-wishers in Tehran

Jafar and Naseem Edrisi are taking little more than their optimism o­n their 20,000km journey.

The expect to be away from home for two years, and have a budget of just $10 to $18 a day (£5 to £9).

"We have different objectives," explains Naseem. "One is to convey a message of peace and friendship to the countries we arrive in."

He went o­n: "Another is to plant saplings in different cities of the world. We want to make a 'green line' around the world, to help the environment."

The couple, who have both worked as tour guides, have also prepared CDs showing their favourite attractions of Iran.

"We want to fix the bad image that has been created of Iran around the world," says Jafar.

Friends and well-wishers at their leaving ceremony

The couple will cycle through northern and southern Europe o­n the first leg of their journey.

After that, they will go o­n to either Africa, or North America, depending o­n what visas they get.

Japan, China, India and Pakistan will form the final, Asian part of their tour. "We cannot predict what will happen," explains Jafar. "It all depends o­n the political situation; we can o­nly plan two months ahead."

Aside from maps, a tent, sleeping bags and cookware, they have also packed a Quran, a Bible and eight books of Iranian poetry into their panniers.

The easiest part of the journey will be the cycling

The couple are funding the trip themselves and have spent the last two years saving and training.

They have also built up a contacts book of friends and relatives in different countries in case they need help.

Despite this, Jafar concedes they still have worries.

"We are concerned about where to sleep at night, about safety and other issues. As o­ne of our friends said, the easiest part of the journey will be the cycling," he said.