Iran and Lebanon's Hezbollah militia are planning to carry out new anti-Israeli attacks around the world, a senior Israeli official involved in counter-terrorism warned on Friday.

"Iran and Hezbollah are planning more attacks overseas," he told reporters, speaking on condition of anonymity and without giving further details.

Israel has been on high alert following three bomb incidents targeting its diplomats in India, Thailand and Georgia on Monday and Tuesday, which the Jewish state has blamed on Tehran.

Top officials have also implicated Iran's Shiite ally Hezbollah in several other foiled attempts to harm Israelis in Thailand and Azerbaijan last month.

"Once again, we call on Israelis overseas to be vigilant, to be wary of suspicious objects, not to accept any such objects and to follow the advice of the security services in the countries where they are," he said.

Asked about reports of an Iranian plot to kill Israeli Defence Minister Ehud Barak in Singapore earlier this week, which were denied by Singaporean and Israeli officials, he said: "We have no information about that."

But he acknowledged that "senior Israeli officials travelling overseas are a prime target."

He also reiterated that Egypt's Sinai Peninsula was still considered to be the "the most exposed place" for Israelis and cautioned against travel there. He also recommended that Israelis avoid travelling to southern Thailand.

The Israeli embassy in Singapore dismissed reports of an assassination plot targeting Barak.

The Israeli embassy's Deputy chief of the mission Michal Sarig-Kaduri dismissed a report in Kuwaiti newspaper Al Jarida that Barak had been targeted for assassination by three members of a Hezbollah-Iranian terror cell during his visit from February 12-15.

The report was widely picked up by Israeli media.

"The ministerial visit went according to plan and no unusual incident occurred. There are absolutely no grounds for this report," she stated.

The Singapore police and an Israeli defence official have also rebutted the report, which stated that the three culprits had been arrested by local authorities with the help of Israeli spy agency Mossad before they could carry out their attack.

Iranian officials have denied any involvement in the incidents in Thailand, India and Georgia this week, rejecting Israeli accusations that the Islamic republic has unleashed a terror campaign.