Thailand’s ousted premier faces the threat of a long ban from politics after another legal ruling against her that will stoke fresh political tensions and deepen criticism over alleged bias in the country’s judicial institutions.

The National Anti-Corruption Commission has indicted Yingluck Shinawatra – who was toppled by the constitutional court in a separate case on Wednesday – on dereliction of duty charges linked to a contentious rice subsidy scheme that has cost the government billions of dollars.

The latest move comes as both government loyalists and the opposition gear up for big rallies that will push the long-running political crisis broadly pitting the old urban elite against Ms Yingluck’s many rural supporters into a still more dangerous phase.