UPDATE 1 — Tunisians stage biggest protest in years against President Saied

(Adds quotes and colour, paragraphs 7 and 9) By Tarek Amara TUNIS, Oct 17 (Reuters) — Thousands of Tunisians joined the largest protest against President Kais Saied in years in the capital on Saturday, accusing him of undermining democracy and mishandling the economy in a growing challenge to his rule. The demonstration, led by the major UGTT labour union and civil society groups, comes as Tunisia grapples with an economic crisis, worsening public services, recurring water and power cuts, and shortages of medicines and essential goods. Saied seized broad powers in 2021 and 2022, dissolving parliament, dismissing dozens of judges and ruling by decree, moves that opponents described as a coup. Rights groups say he has intensified a crackdown on civil society, journalists and opposition figures. Saied rejects those allegations, saying he is not a dictator, and has accused his opponents of engineering economic crises to fuel social unrest. In a rare show of unity, opposition parties from across the political spectrum joined lawyers, doctors, journalists, unemployed people and civil society groups in marching along Habib Bourguiba Avenue, a focal point of the 2011 protests that helped t