An Argentine court has declared unconstitutional a controversial agreement between Buenos Aires and Tehran to investigate the Amia bombing.

Prosecutors in Argentina suspect that the 1994 attack on a Jewish community centre was ordered by Iran and now a federal court has found that the joint truth commission, set up at the beginning of 2013, is unlawful.

The government of Cristina Fernandez de Kirchner has confirmed that it will appeal to the Supreme Court, though the Argentine government is known to have become frustrated with the lack of progress in the investigation on Iran’s part.

No one has been convicted of the attack on the Amia centre in Buenos Aires, in which 85 people were killed and 300 injured.

The Argentine chancellor, Hector Timmerman, who is Jewish, furiously criticised the court, saying “those who are celebrating this ruling are the Iranians accused of the attack and those who want to hide the truth”.

However, federal judge Eduardo Farah declared the original agreement unconstitutional because it interfered with the Argentine justice system, increased the division of power and took no account of the views of the victims of the attack.