NAIROBI, Kenya (CNN) -- Two Iranian nationals, accused of plotting to plant explosives in Kenya, were in the advanced stages of planning of a terror attack in Kenya, according to a senior Kenyan government official familiar with intelligence updates.

"We do not want to speculate exactly on the seriousness of their plan," the official said, adding the suspects may have wanted to use Kenya as a transit point to hit targets in neighboring countries. "We are still working to uncover it. We don't allow organizations or countries to commit terror in our country, and we will prosecute such acts accordingly."

The suspects were arrested June 19 in Nairobi and led security officials to 15 kilograms (more than 30 pounds) of RDX explosives hidden at a Mombasa golf club, on Kenya's coast, according to court documents.

"The amount of explosives they uncovered was very powerful and could have caused a lot of damage and loss of life if used," the official said.

The two Iranian suspects, Ahmad Abolfathi Mohammed and Sayed Mansour Mousavi, appeared in a Nairobi court June 25 charged with two counts: preparation to commit a felony and being in possession of explosives without a license.

According to court transcripts seen by CNN, both Mohammed and Mousavi denied the charges and said they were wrongly accused. They also alleged Kenyan police had tortured them.

Mohammed said he was given an injection by a Kenyan intelligence agent. The presiding magistrate said the matter would be investigated and denied the pair bail, ruling they would be a flight risk.

The Iranians' attorney, David Kirimi, declined to comment, saying he wished to consult with his clients.

If proven guilty, the case could be linked, security analysts said, to a series of plots and attacks, allegedly by Iranian operatives, targeting Israeli diplomats.

The Israeli prime minister's office reacted swiftly to the latest allegations in Kenya.

"Iranian terror has no borders. ... Now its intention to execute terror attacks in Africa is being revealed. The international community must fight against the world's biggest exporter of terror."

Iran's Foreign Ministry spokesman hit back Tuesday, saying officials are trying to establish the identity of the two men.

"When it comes to Iranian nationals, coverage of the events are exaggerated," said the spokesman, Ramin Mehmanparast, in Tehran.

The arrests of the Iranians and discovery of explosives came in the midst of a U.S. Embassy warning of an "imminent threat" of terror attacks in Mombasa, with the embassy taking the unusual step of suspending U.S. government travel to the coastal city until the end of July.

It was the latest in a string of warnings to U.S. citizens in Kenya.

But security analysts and evidence from recent incidents suggest that the major terror threat to Kenya may be from Somalia, not Iran.

A series of low-grade grenade attacks, blamed on sympathizers of Al-Shabaab, culminated in simultaneous attacks Sunday by masked gunmen on two churches in Garissa, Kenya.

The gunmen lobbed grenades into Catholic and African Inland churches and then opened fire on the parishioners in the ensuing panic, according to Kenyan police. Seventeen people were killed, and more than 40 injured. No one has claimed responsibility, but Kenyan police said they suspect Al-Shabaab.

While Al-Shabaab has been linked to al Qaeda and Al Qaeda in the Arabian Peninsula, experts said they believe there is little chance they would align themselves with Iranians.

"Iranian operatives have had little involvement with East and Horn of Africa militant groups," said Rashid Abdi, a Somali terror expert and religious editor at Nation Group, "and mostly Sunni Somalis would regard Iranians Shiites with mistrust.

"But stranger things have happened," he added.

The terror allegations come at an awkward moment in economic relations between Kenya and Iran.

Kenya has agreed to import 4 million tons of Iranian oil per year, signing a memorandum of understanding with Tehran in June, CNN affiliate KTN reported, citing statements from Energy Ministry Permanent Secretary Patrick Nyoike.

The Iranian Foreign Ministry spokesman alleged that Kenyan-Iranian relationships were being deliberately sabotaged. "Making public this incident coincides with positive economic moves between the two countries," Mehmanparast said. "We are suspicious of the motives behind the publicizing of this kind of news about Iranian nationals in countries where we have close and friendly relations."