The Swiss government said on Wednesday it had tasked an expert with clarifying supervision of the Swiss National Bank after its chairman Phillipp Hildebrand resigned over a currency trading scandal.

After auditors found the currency trade, made by Philipp Hildebrand's wife just a few weeks before the SNB imposed a cap on the franc, was in line with the SNB's rules, critics said they were too lax.

At its meeting today, the Federal Council commissioned various follow-up assignments aimed at showing any need for action in the wake of the resignation of the Chairman of the Governing Board of the Swiss National Bank, it said in a statement.

The evaluation is to outline the tasks and responsibilities currently regulated in the National Bank legislation in connection with supervision of the SNB and the constitutional room for manoeuvre in terms of possible amendments to the applicable rules, it also said.

Finance Minister Eveline Widmer-Schlumpf said earlier this month that such an evaluation would be commissioned.

The SNB's independence is enshrined in the constitution.

(Reporting by Catherine Bosley)