Swiss investigators are probing Nicolas Leoz, a veteran FIFA official in South America, in their widening inquiry into alleged corruption in world football, a Swiss newspaper said on Saturday.

Leoz, an 86-year-old Paraguayan, headed the regional football organisation Conmebol from 1986 to 2013 and was a member of FIFA's executive committee for 15 years.

Swiss officials are also investigating Eduardo Deluca, a long-term general secretary of Conmebol, after private bank Pictet tipped them off in June about suspicious movements in an bank account, the Zurich daily Tages Anzeiger said.

Millions of Swiss francs were paid into the account by FIFA and by Japanese advertising agencies, and much of the money was then transferred to Paraguay, it said.

Suspicions are also being directed at an account with the Credit Suisse bank, it said.

The Swiss prosecutor's office declined to comment on the report.

Leoz's attorney said his client was unaware of any inquiry while Deluca could not be contacted, the paper said.