Marc Thompson said the "hardest thing is not knowing" where his twin brother Ben is.
The 34-year-old from Haverfordwest has been missing since Saturday, after he watched Wales' Six Nations game at the Millennium Stadium.
He told our Correspondent Carole Green that this would be "very out of character" for him not to contact his family.
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Hayley Ladd fired home a late free-kick as Wales beat Kazakhstan 1-0 to stay top of their World Cup qualifying group.
A cold and frosty night with ice patches, frost and snow falling over the hills! it's going to be a wintry start to the weekend!
Campaigners are calling on the Welsh Government to launch a public information campaign.