Thailand's former Prime Minister Yingluck Shinawatra has entered a plea of not guilty at the start of a trial that could see her jailed for a decade.

The ousted premier appeared at Bangkok's Supreme Court on Tuesday to formally hear the charges against her of dereliction of duty in overseeing a rice subsidy scheme that lost billions of dollars.

Critics say the case is part of a politically motivated campaign against her family.

Yingluck was ousted from her post by a court decision that came two weeks before the military staged a coup last May.

The same charges also led to her impeachment in January by the military-appointed legislature, which banned her from politics for five years.

Her brother, former Prime Minister Thaksin Shinawatra, was ousted in a 2006 coup.