The Corner won the business after a contested pitch. Coca-Cola handled the process, which began around six weeks ago, directly. The Corner will now be charged with creating an above-the-line campaign for Oasis across a range of formats in 2014.
The Corner saw off competition from 101 to win the Oasis pitch, while the incumbent, VCCP, said it declined to re-pitch. However, sources at Coca-Cola contradicted VCCP's statement and suggested the agency was involved.
A spokeswoman said: "We can confirm we have appointed The Corner to handle the ATL work for Oasis. This process was taken to a pitch to three agencies and we do not have any further comment to make beyond this.
"The Corner will handle all creative work for the brand as we go into 2014."
VCCP had held the Oasis account since 2010, when it won the business without a pitch. Mother had previously worked with Oasis, winning the account in 2001, but declined to re-pitch for the work in the 2010 process.
In March, Coca-Cola appointed MediaCom to its £30 million UK media planning and buying account – which includes Oasis – ending a 12-year relationship with Vizeum and its predecessor agency, BBJ.
The Corner declined to comment.