ATHENS, Greece (AP) — A Greek deputy minister resigned on Thursday following allegations of evidence tampering at the site of the 2023 rail disaster that claimed 57 lives when two trainswere involved in a head-on collision.

Christos Triantopoulos, deputy minister for civil protection, stepped down following claims by the main opposition party that he participated in unauthorized alterations at the crash site. He denies the accusations.

The fatal collision occurred near Tempe, in northern Greece, when a passenger train was incorrectly routed onto the same track as an oncoming freight train.

Triantopoulos has said his presence at the site following the crash was part of the government’s efforts to assist the victims’ families.

He said his resignation was to help the government after he had been unfairly targeted.

Delays in the disaster investigation have intensified pressure on the conservative government ahead of the two-year anniversary of the crash on Feb. 28. The tragedy has triggered massive public protests and political controversy, with victims’ families demanding answers about the freight train’s cargo, which they suspect included illegal flammable materials.