The National Accountability Bureau (NAB) on Monday filed a new reference in the accountability court against PML-N President Shahbaz Sharif and his son Hamza Shahbaz in connection with the Ramzan Sugar Mills case, DawnNewsTV reported.

The father-son duo, leaders of the opposition in the National and Punjab assemblies respectively, have been nominated as the primary accused in the reference.

According to the NAB, Shahbaz Sharif, being chief minister of Punjab, had issued a directive for the construction of a drain in Chiniot district primarily to benefit the sugar mills owned by his sons.

The PML-N president misused his authority as Punjab chief minister to benefit factories owned by his sons, a senior official had told Dawn last month.

The bureau alleges that Shahbaz and Hamza have "fraudulently and dishonestly" caused a Rs213 million loss to the national exchequer. It claims to have obtained "sufficient incriminating" material and evidence during investigation and prayed the court to try and punish the aforementioned accused.

Both Shahbaz and Hamza have pleaded not guilty to the charges.

Shahbaz has already been indicted in the Ashiyana Housing reference, whereas Hamza also faces an inquiry in an income beyond means case.