The court of first instance in the capital Abidjan on Friday ordered the suspension of the congress, which had been planned for Saturday to elect a new Democratic Party leader before a presidential election in 2025.
The ruling followed an urgent request from two senior party members alleging opacity and irregularities in the organization of the congress, court documents seen by Reuters show.
The complaints were not directly aimed at Thiam, but the plaintiffs said that a day before the congress, they did not have the names of the shortlisted candidates for the presidency or the names of party members who will be voting.
The court sided with the plaintiffs and ordered the postponement of the congress.
The winner of the contest to lead the Democratic Party, known by its French acronym as the PDCI, stand the chance of being the party's candidate in the presidential election.
Since leaving Credit Suisse, Thiam, 61, has returned to politics in Ivory Coast, and submitted his candidacy last month to lead the party that ruled the West African nation from independence to the early 2000s.
Thiam's campaign team said in a statement on Saturday that police had cordoned the hotel in Abidjan where the congress was scheduled to hold. It urged supporters to avoid the area and wait for further instructions from the party.
Within the party rank and file, he is seen as an outsider with no strong grassroots base but with enough means to garner support.
Thiam served as a minister in Ivory Coast under former president Henry Konan Bedie. He left the West African country after Bedie's ouster in a 1999 military coup and worked for consultancy firm McKinsey, and insurers Aviva and Prudential, before his appointment as Credit Suisse CEO in 2015.
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