Dyfed-Powys Police are appealing for help to trace missing Carmarthen woman.
April Penelope Tanner, 44, was last seen at the junction 47 services of the M4 in Penllergaer, Swansea, at around 3.45pm on Saturday, December 29.
She is described as about 5ft 5ins, medium build, with shoulder length, blonde, wavy hair. She was last seen wearing a red jacket/coat, patterned blouse and navy leggings.
A Dyfed Powys Police spokeswoman said: "We know that she took a taxi from Carmarthen to Junction 47 then travelled to London.
"Anyone with any information relating to her whereabouts, or who may have seen her or been in contact with her is asked to contact us on 101."