The Swiss cabinet says it will destroy sensitive documents in a nuclear-arms smuggling case despite demands that the complete file be handed over.

President Hans-Rudolf Merz told Swiss public radio on Wednesday that ministers still planned to shred certain documents believed to contain nuclear-warhead designs. Switzerland, a non-nuclear power, is not permitted to have such plans under the Nuclear Non-Proliferation Treaty.

Investigators say the documents are crucial evidence in the Tinner family nuclear-smuggling case. Urs, Marco and Friedrich Tinner, Swiss engineers with dealings in a centrifuge business, have been the focus of an investigation into suspected ties to Abdul Qadeer Kahn, the father of Pakistan's nuclear programme and a renowned weapons smuggler.

The Tinners have maintained their innocence. Urs Tinner has claimed he was working for American spies when word leaked that a Libya-bound ship in an Italian port was carrying centrifuge parts needed to make a bomb. The bust forced Libya to admit its nuclear ambitions, which it later abandoned.

The cabinet secretly destroyed the most sensitive documents in the case in November 2007 but not before making copies. Merz said on Wednesday that those copies would now be destroyed.

The International Atomic Energy Agency (IAEA) has said that Switzerland is capable of safely storing the documents. Parliamentarians have also argued there is no international obligation to destroy the file.

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