Sir Mo Farah, one of Britains most prolific athletes, condemned President Donald Trump s executive order banning people from certain Muslim countries and raised concern it would keep him from returning to his home in the U.S.

Farah, a four-time Olympic gold medallist knighted by Queen Elizabeth II earlier this year for being the most successful track athlete in the countrys Olympic history, is currently training in Ethiopia and not scheduled to return to his home in Portland, Oregon, for several weeks. In a heartfelt Facebook post on Sunday, he condemned Trumps executive order.

On 1st January this year, Her Majesty The Queen made me a Knight of the Realm, he wrote. On 27th January, President Donald Trump seems to have made me an alien.

Farah is a British citizen born in Somalia, one of the countries on Trumps list. He has been living in the U.S. for the past six years. In his post, he described how hes been working hard, contributing to society, paying my taxes and bringing up our four children in the place they now call home while training with the Nike Oregon Project in Portland, Oregon.

Now, me and many others like me are being told that we may not be welcome. Its deeply troubling that I will have to tell my children that Daddy might not be able to come home - to explain why the President has introduced a policy that comes from a place of ignorance and prejudice, he wrote.

Representatives for Farah clarified with the sports news outlet FloTrack that he does not have dual nationality with Somalia, and they are seeking further clarification on whether hell be barred from entering the United States.

[T]he situation at this stage is still unclear. Mo is a British citizen with a British passport and does NOT have dual nationality or hold a Somalian passport. However, he was born in Somalia before moving to the UK at the age of 8 and becoming a British citizen.

We are seeking to clarify the situation with the US authorities. Mo is currently at a training camp and is not planned to return to the US for a number of weeks. However, as Im sure you can appreciate he and [his wife] Tania want to understand the direct impact on them (if any) as a matter of urgency.

Farahs concerns may be justified, given how much Trumps Muslim ban proposal has evolved over the last year and how much potential it has to expand . Authorities scrambled to enact the order after Trump signed it Friday.

If Farah is detained at a U.S. airport upon return, it wont be his first time.

Because of my Somali origin I get detained every time I come through U.S. Customs, he said in 2012 after being stopped on his way home from the London Olympics. This time I even got my medals out to show who I am, but they wouldnt have it.