The Nigerians announced the arrests Thursday, the day after Argentina's state prosecutor, Alberto Nisman, accused Iran. Hezbollah's patron, of establishing a network of sleeper cells across Latin America, and three weeks after two Iranians were jailed for life in Kenya for plotting attacks on Western and Israeli targets.
Also on Thursday, the U.S. State Department said there was a "marked resurgence" of international plots and attacks in 2012, most notably in Europe and Africa, by Hezbollah, the elite Al-Quds Force of Iran's Revolutionary Guards, or both.
"Iran and Hezbollah's terrorist activity has reached a tempo unseen since the 1990s," the State Department observed in its annual global terrorism report.
Iran's intelligence services, often employing Hezbollah which they helped to create in 1982, have been active against the United States and Israel in recent years as they seeking to retaliate for the systematic assassination of Tehran's nuclear scientists and the sabotage of its nuclear program.
Hezbollah has its own reasons, primarily to take revenge against Israel, which it blames for Feb. 12, 2008, assassination in Damascus, Syria, of their iconic military leader, Imad Mughniyeh.
On May 6, Two Iranian nationals suspected of belong to the al-Quds Force, the Revolutionary Guards covert external operations arm which often works with Hezbollah on foreign operations, were sentenced to life imprisonment in Kenya for plotting attacks against U.S., British and Israeli targets in Nairobi.
When they were arrested in June 2012 they led authorities to a cache of 33 pounds of RDX, a powerful military-grade explosive, hidden near a golf club at the Indian Ocean city of Mombasa. Another 185 pounds of the RDX is missing.
In Nepal, Israeli Embassy personnel in Kathmandu seized an Iranian carrying a forged Israeli passport "acting suspiciously" at the embassy and handed him over to security authorities.
The Iranian, Mohsin Khosravian, had lived in Bangkok since 2004 and acquired the fake Israeli passport in Kuala Lumpur, Malaysia.
It wasn't known whether he was linked to attempted attacks on Israeli targets in Thailand and other Asian cities by an Iranian cell. Several were arrested in Bangkok in early 2012.
Thailand seems to have been a primary target for Hezbollah. Hussein Atris, a Lebanese holding a Swedish passport, was detained in Bangkok in January 2012.
Swedish media say he ran a hairdressing salon in the Swedish city of Gothenburg and married a Swedish woman in 1996. One of his relatives, Mohammad Atris, was involved in the Iranian-led assassination of four Kurdish opposition figures in a Berlin restaurant in 1992.
Thai police said Hussein Atris had an accomplice and issued a composite portrait that bears a striking resemblance to a notorious Hezbollah operative known as Naim Haris. Israeli intelligence says he's in charge of recruiting Hezbollah agents worldwide.
On Feb. 20 a court in Cyprus sentenced Hossam Taleb Yaacoub, a 24-year-old Lebanese with Swedish citizenship, to four years in prison for helping Hezbollah plot attacks against Israeli tourists on the Mediterranean island.
Yaacoub, who confessed he was with Hezbollah, was arrested in July 2012, about the same time that five Israeli tourists were killed in a bombing in the Bulgarian Black Sea resort of Burgas in an attack that appeared to be similar to the one Yaacoub was scouting out.
The Burgas bomber, identified by police as a Hezbollah activist, was also killed but it's not clear whether the attack was planned as a suicide bombing.
Bulgarian authorities say two other Lebanese-born Hezbollah members, traveling on genuine Australian and Canadian passports, escaped to Lebanon.
Several of these cases involve suspected Hezbollah operatives using fake or genuine Western passports, suggesting they were recruited because they had lived in Western countries and obtained citizenship or had been trained to operate in Western society under false identities.
Hezbollah formed a special group in the 1990s that recruited such operatives, including fair-skinned Lebanese who could pass as North Americans or Europeans.
One graduate infiltrated Israel on a bombing mission using a Western identity. But he blew himself up in a Jerusalem hotel while he was assembling his bomb.