COLOMBO, Sri Lanka — Sri Lanka’s prime minister appeared Monday before a commission that is probing alleged wrongdoing in the sale of government bonds that opposition lawmakers say led to a loss of about $1 billion.

Prime Minister Ranil Wickremesinghe said his government has “nothing to hide.”

He told the commission that the government needed money to pay for projects such as road construction that the previous administration had carried out, but were never included in the official budget.

The scandal has tainted Wickremesinghe’s government, which came to power promising to eradicate corruption.

The commission was appointed by President Maithripala Sirisena amid mounting criticism of former Central Bank Gov. Arjuna Mahendran by opposition lawmakers and others. Mahendran was appointed by Wickremesinghe.

Most of the bonds were sold to a company owned by Mahendran’s son-in-law, who is accused of making massive profits.

The commission is to complete its report next month, and Sirisena has vowed to punish anyone found guilty of wrongdoing.

Sirisena and Wickremesinghe, who are from different political parties, formed a national unity government that took power in 2015 promising to tackle corruption and wipe out alleged financial irregularities under the previous regime.

The government has denied that $1 billion was lost in the bond sale.