MEXICO CITY (Reuters) – Pressure is growing for Mexican authorities to release prominent labor lawyer Susana Prieto, arrested a week ago at a protest, with two U.S. unions concerned about a rights clampdown ahead of a new regional trade deal.

Prieto, who last year helped organize unprecedented strikes at several dozen manufacturing plants in the northern border city of Matamoros, was charged with threats, inciting a riot, coercion and crimes against public servants. She has denied the charges.