The lender did not give details of the provision but said it had a N38bn ($125m) exposure to 9mobile.
UBA said the exposure was secured, and part of a syndicated loan with 12 other banks extended to Etisalat Nigeria four years ago.
Local banks have agreed an extension to a $1.2bn loan made to 9mobile, pending the mobile operator finding new investors.
However, some lenders outside the syndicated facility are making provisions.
“We have taken a general loan loss provision on Etisalat,” the Chief Executive Officer, UBA, Kennedy Uzoka, told an analysts call.
“It’s instructive to note that Etisalat has reasonably turned around in terms of subscribers and revenues,” he said, adding that the bank was one of the lenders managing its receivables.
Zenith Bank said this month it had made a 30 per cent provision on its loan to 9mobile, the country’s fourth-largest telecoms group.
The Central Bank of Nigeria and the Nigerian Communications Commission had last month stepped to save Etisalat Nigeria from collapse and prevented banks from placing it into receivership, prompting a board, management and name change.
Last week, UBA said its first-half pre-tax profit rose by 66 per cent to N57.5bn, while its non-performing loan ratio rose to 4.2 per cent in the half-year, up from 3.9 per cent a year earlier.
According to Uzoka, Nigeria is the lender’s largest market, but that he expects the bank’s African operation to contribute about 50 per cent to group earnings over the medium term from 32 per cent in the first half of the year.
He said the lender had applied to British regulators for a banking licence.
UBA shares, which have gained by 114 per cent so far this year, dipped 0.52 per cent to N9.58 on Tuesday.