Media reports say that the Swiss Office of the Attorney General has launched an investigation into the state-backed takeover of Credit Suisse by UBS, Switzerland's largest banking group.

Last month, UBS agreed to take over the troubled Credit Suisse for 3 billion Swiss francs, or about 3.2 billion dollars.

The Financial Times reported that Switzerland's Federal Prosecutor opened the probe on Sunday, looking into potential breaches of Swiss criminal law by government officials, regulators and executives at the two banks.

The paper said one focus of the probe concerns sensitive information from the negotiations that was leaked outside, citing a person familiar with the investigation.

The Swiss prosecutor is reportedly already in contact with the federal and cantonal governments and is likely to seek to interview key officials in relation to the takeover.

Meanwhile, a local Swiss newspaper reported on Sunday that UBS plans to cut 20 to 30 percent of the workforce after takeover procedures have been completed. It said the figure could be up to 36,000 employees globally and 11,000 in Switzerland only.

Critics have been questioning some of the tough measures taken by Switzerland's financial authorities regarding the emergency takeover. The authorities instructed Credit Suisse to completely write down its AT1 bonds as the government provided support for the group's takeover by UBS.