The Serious Fraud Office (SFO) has been in contact with Berwin Leighton Paisner (BLP) in relation to a bribery investigation being undertaken by South African prosecutors.
The South African investigation is looking into allegations that supplier of military aviation electronics Thales bribed the former vice-president of South Africa Jacob Zuma.
The South African prosecutors contacted the SFO requesting information from BLP after they suspected a £69,000 bribe, allegedly paid to Zuma, was channelled through the firm's client account.
BLP was holding money on behalf of one of its former clients after the firm managed to settle a separate dispute related to the telecoms industry.
There is no suggestion that BLP had acted improperly or was aware of any wrongdoing.
A BLP spokesman confirmed that several months ago the firm had been approached by the South African authorities via the SFO.
"Our client wasn't involved in the defence industry and wasn't connected to Thales in any way. Having provided the information requested, we're not aware of any outstanding questions," said the spokesman.
Thales has denied any wrongdoing and is set to defend itself against the bribery allegations.
Thales chief executive Alex Dorrian was one of a group of defence company bosses who lobbied the UK Government to stop the SFO inquiry into the al-Yamamah arms deal with Saudi Arabia.
The SFO investigation was into an alleged £60m slush fund paid by BAE Systems, the al-Yamamah contractor, to senior members of the Saudi royal family.