By Eyk Henning 

FRANKFURT--German customs authorities have confiscated documents from a former unit of Royal Bank of Scotland PLC showing that family members of the widespread bin Laden clan were among its clients.

Some bin Laden family members are respected businesspeople, such as the owners of Saudi Binladen Group, the largest construction company in Saudi Arabia.

RBS moved quickly on Sunday to stress that it didn't do business with Osama bin Laden.

"We didn't take care of Osama bin Laden's financials at any point of time, nor did we deal with his immediate relatives. His [Osama bin Laden's] personal finances were never of interest for [former RBS unit] Coutts International," the former RBS unit, the Edinburgh-based bank said.

German television network RTL reported on the documents, citing German newsweekly Focus, which broke the news earlier this weekend, suggesting there might be a link between the state-controlled British lender and the bin Laden family.

RBS November last year sold its Coutts Cayman operations, which were part of its exclusive Coutts private-banking arm, to law and fiduciary firm Appleby Global. RBS still owns Coutts, which counts Britain's Queen Elizabeth II among its clients.

Appleby Global couldn't immediately be reached to comment.

As part of the transaction, RBS shipped two containers with documents to Geneva from the Cayman Islands a couple of weeks ago, people familiar with the matter said.

German customs officials at the Hamburg seaport opened those containers and searched the documents, these people said.

German authorities have evaluated the findings in the last couple of weeks amid a broader investigation into the banking industry, these people said. It remained unclear on Sunday whether the containers were opened as part of the investigation.

The Hamburg customs office couldn't be reached to comment on Sunday.

Authorities from the state of North Rhine-Westphalia have bought several CDs with data on German clients of Switzerland-based banks to investigate potential tax evasion. The efforts by the state's prosecutors are controversial because the CDs had been stolen by individuals who then sold them to government authorities.

Write to Eyk Henning at eyk.henning@wsj.com

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