It was just a matter of time. The UK is reported to have joined a host of other international agencies in undertaking their own investigations into alleged corrupt practices involving Malaysia's state fund, 1Malaysia Development Berhad.

Although not confirmed, the involvement of the UK could be due to the alleged involvement of the Royal Bank of Scotland in the transfer of the state fund's monies out of Malaysia. It is alleged that RBS Coutts in Zurich, which is owned by RBS, is one of the banks that had transferred the state fund's money out of Malaysia.

The UK's Serious Fraud Office is said to be looking into allegations pertaining to the state fund that were published in the Sarawak Report, a London-based news website focusing on the state of Sarawak. The website is founded by Clare Rewcastle-Brown, the sister-in-law of former UK Prime Minister Gordon Brown.

The Times reported earlier this week that it has seen documents linking RBS Coutts in Zurich to the transfer of money out of Malaysia from the state fund. "The bank faces questions over its compliance checks and the beneficiaries of the money," the newspaper said.

RBS Coutts has said that it could not comment because of client confidentially. Similarly the Serious Fraud Office would not comment on the case, The Times reported.

The controversy surrounding Malaysia's Prime Minister Najib Razak further deepened when Saudi Arabia claimed last week that the close to $700m transferred into the politician's personal bank accounts were not a political donation as claimed earlier but were for investment purposes.

The funds in Najib's account drew widespread interest after the Wall Street Journal reported that the money had come from heavily-in debt 1MDB. Najib had strongly denied this and he has since been cleared by the local anti-corruption commission which said that the money came from unidentified donors and not 1MDB as alleged.

Saudi Arabia's Foreign Minister Adel al-Jubeir said that the funds were part of a business deal. "It is a private Saudi citizen. I believe, and the funds went to an investment in Malaysia," he said last week. Claims that Najib had allegedly returned $620m to the royal family because the funds were not utilised could not be independently confirmed.

News reports claim that a member of the royal family and an associate of the family, speaking on condition of anonymity, had said that the money had come from a Saudi prince and that it was not a donation as claimed earlier by the Malaysian authorities.

On 4 February, France announced that prosecutors would investigate claims that Najib took kick-backs as part of a $1.2bn (£0.8bn) arms deal. News organisations in the US have reported that the FBI was investigating allegations of money laundering at 1MDB and that the US Federal jury was looking into Najib.

That is not all, Switzerland has said last month that it has asked Malaysia formally for help with its investigations into possible violations of Swiss laws related to bribery of foreign officials, misconduct in public office, money laundering and criminal mismanagement at the state fund. In Singapore, the authorities have seized a large number of bank accounts in relation to 1MDB.

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