The Swiss attorney general's office says it has expanded a probe into suspected embezzlement of a Malaysian state investment fund to investigate two former Emirati officials.

Investigations into the fund, 1MDB, have indicated that $4 billion earmarked for investment in development projects in Malaysia may have been misappropriated from state-owned companies.

Switzerland, which says part of the money was transferred to accounts there, last year opened an investigation of two former fund officials and persons unknown on suspicion of bribery and money laundering, among other offenses.

The attorney general's office said Tuesday the two Emiratis now under investigation were in charge of Abu Dhabi sovereign funds. The probe centers on how 1MDB subsidiaries obtained a guarantee from Abu Dhabi to repay bonds issued to finance investments in power plants.