South Korea’s Foreign Ministry on Wednesday at a briefing announced the outcome of a government investigation into the May 4 attack on a bulk carrier operated by shipper HMM in the Strait of Hormuz.

“Various pieces of evidence point toward Iran,” said First Vice Foreign Minister Park Yoon-joo, adding that Seoul had not conclusively determined who was responsible or whether the attack was intentional.

The analysis showed that the ship, named Namu, was attacked twice and while the first warhead did not explode, a second did. Components in the debris indicated the objects were likely made in Iran, the ministry said.

“Their engines were similar to turbojet engines made in Iran,” Park said, noting that one component had markings that appeared to be used by an Iranian manufacturer. The warheads resembled those used in Iranian anti-ship missiles, the Noor or Qader, Park said.

Saeed Koozechi, the Iranian ambassador to South Korea, denied Iran’s role in the South Korean vessel attack saying his country “took no part” in it, local news agency Yonhap News reported.

The Iranian embassy in Seoul did not immediately respond to a request for comment.

South Korea summoned the Iranian ambassador to share the results of the investigation and deliver a protest message, according to the ministry.