"The three captured members of the Iranian Revolutionary Guard are now being questioned by Saudi authorities", it said, citing a Saudi official.
That statement made no mention of explosives and did not detail what type of weapons were found, though it said they were for "subversive purposes".
The news, reported on the Saudi national news agency, said that the Kingdom of Saudi Arabia "stressed its determination to combat and eradicate terrorism and its sources, as a part of the country's permanent objective to protect its national security against any external aggression".
Saudi Arabia said its navy captured three members of Iran's Revolutionary Guard aboard a small boat laden with explosives as it headed toward an oil platform in the Gulf. "It was captured with the three men on board, the other two escaped", the Saudi information ministry said in a statement on Monday.
Quoting an "official source", the SPA report said just after midnight on June 16, 2017, three boats bearing flags in white and red flags rushed to the Marjan offshore oil field off the Eastern Province.
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Tensions between Sunni-led Saudi Arabia and Shiite-dominated Iran are chronic.
Earlier on Saturday, the Interior Ministry's director general for border affairs, Majid Aqa-Babaei, said the incident occurred after two Iranian boats fishing in the Persian Gulf strayed from their course due to bad weather.
Aghababaie said "even if the boats had entered Saudi waters, the coastguard were not authorised to open fire". "When Iran looks at ISIS it sees Saudi Arabia".
Relations between Saudi Arabia and Iran were already strained but escalated after Saudi Arabia, the United Arab Emirates, and other allies cut ties with Qatar two weeks ago.