Iran's intelligence ministry showed weapons and ID cards allegedly belonging to those arrested [EPA]
Heydar Moslehi, Iran's intelligence minister, has said that his country has arrested more than 10 people under suspicions of espionage after the country infiltrated Israel's "intelligence system".
Tuesday's announcement came a day after Iran's intelligence services said that they had arrested suspects in the assassination a year ago of a nuclear physicist, in a months-long covert operation that they said led them to penetrate Israel's Mossad spy agency.
Iran blames Mossad for the murder of Masoud Ali Mohammadi, a Tehran University physics professor, who was killed by a bomb-rigged motorcycle that exploded outside his house as he was leaving for work in January 2010.
One of those arrested has appeared on Iranian television to apparently confess to the assassination of the nuclear physicist.
In a news conference on Tuesday, Moslehi said: "More than 10 people were arrested ... we were able to identify their [Mossad contacts] and to infiltrate them.
"We were able to infiltrate the Zionist entity's apparatus ... we were able to infiltrate deep into Mossad."
Mohammadi, 50, had no prominent political voice, no published work with military relevance and no declared links to the country's nuclear programme, though his work included some aspects of nuclear theory.
Moslehi said: "It's been proven to us that the Zionist Regime opposes any scientific progress in the region and among Islamic countries.
"So all prominent scientists of the region face the threat of being assassinated by the Zionist Regime.
"Due to our duty, we shall inform the Islamic countries and other countries of the region in that regard."
During the briefing, weapons and ID cards allegedly belonging to the arrested people were also shown to the media.
Al Jazeera's Alireza Ronaghi, reporting from Tehran, said: "The most important thing to remember here is that the intelligence ministry has been under enormous pressure, throughout last year since January 2010, when Dr Ali Mohammadi was assassinated.
"In a way, the intelligence ministry was under pressure to come out and say something about its activities and although it's not saying much at the moment, it's crucial for them to say these things to relieve the pressure that they are under.
"Many, even supporters of the government, are criticising the intelligence ministry and they were accusing spymasters of not doing enough to ... check intelligence activities, to prevent such things from happening."
Iran has also accused the intelligence services of Israel and the US of being behind bomb attacks against two top nuclear scientists on November 26.
Majid Shahriari died in one of the attacks and Fereydoon Abbasi Davani was wounded in the other.
Washington has rejected the allegations as "absurd".
Israel, believed to be the only country in the Middle East with nuclear weapons, the US and its allies, accuse Iran of using a civilian nuclear programme as cover to build atomic weapons.
Iran denies the charge, saying it wants to use nuclear power in order to be able to generate electricity.
Source: Al Jazeera and agencies