Mo Farah felt he had to speak out over a "crazy, unfair and scary" travel ban imposed by United States president Donald Trump in order to provide a voice for innocent citizens.

Four-time Olympic champion Farah last month criticised Trump after he prevented nationals from seven countries from travelling to the US for 90 days under an executive order.

British athlete Farah, who successfully defended his 5,000 metres and 10,000m titles at Rio 2016, moved to the United Kingdom from Somalia as a child but has lived in the US since 2011.

Farah was able return to his Portland home after it was clarified that the exclusion would not apply to him.

Trump said he will issue a new executive order after his initial travel ban was blocked by federal appeals court judges and Farah has revealed why he felt he had to let his opinions on the matter be known.

"It was crazy and unfair," said Farah. "That's why I stood up and spoke out.

"They have made changes for people like me but the hard part was living in the US for six years and going to a training camp and hearing the news I can't go back and see my kids.

"That was scary and it was important for me to speak out as there are a lot of innocent people out there who couldn't say anything.

He added: "I'm not a politician and as an athlete you don't like to get involved in politics but sometimes when it affects you – it affected me and my family – you have to speak up. And a lot of people got behind me."