By Myra MacDonald
LONDON, Oct 20 (Reuters) - A suicide bombing in Iran near the border with Pakistan has exposed a deep sectarian faultline in a region already destabilised by the spillover from the Afghan war, drug smuggling and nationalist insurgencies.
Analysts say the ethnic Baluch insurgent group Jundollah which Iran blamed for Sunday's attack is increasingly inspired by Sunni Islamist militants based in Pakistan.
And that poses risks both to Shi'ite Iran as well as highlighting the challenges faced by Islamabad in battling Islamist groups which are now threatening Pakistan itself.
"An ethnic conflict has turned sectarian," said a study by the Norwegian Defence Research Establishment published in July.
"Extremist groups such as Jundollah are seemingly copying the practices and discourse of Pakistani movements," it said.
Fifteen Iranian Revolutionary Guards and 27 others died in Sunday's suicide bombing in one of the deadliest attacks in years on Iran's most powerful military institution.
The bombing happened a week after gunmen attacked the Pakistan Army's own headquarters -- an assault which highlighted the strength of Sunni Islamist militants even as the military battles them in their stronghold in South Waziristan.
Jundollah, which analysts say operates across the porous borders between Iran, Pakistan and Afghanistan, and not to be confused with a Pakistani group of the same name, denies any links to regional militant groups.
But its use of suicide bombings and Shi'ite targets -- the bombing of a Shi'ite mosque in Zahedan in Sistan-Baluchestan in May was also blamed on Jundollah -- have underpinned views it follows a sectarian rather than nationalist agenda.
Its leader Abdolmalek Rigi has been quoted as saying he wants equal rights for Sunnis and ethnic Baluchis in Iran, but makes no territorial claims.
In that respect, Jundollah is quite different from Baluch rebels on the Pakistan side of the border fighting for independence or autonomy for Baluchistan.
"The Jundollah seems to be more a Sunni extremist than a Baluch nationalist organisation," wrote Indian strategic analyst B. Raman in a note on the latest attack in Iran.
Analysts have linked it to the Lashkar-e-Jhangvi (LeJ), an anti-Shi'ite Punjab-based group, which works closely with the Pakistani Taliban, or Tehrik-e-Taliban (TTP). Both in turn are believed to have close ties to al Qaeda.
Iran has accused the United States, Britain and Pakistan of involvement in Sunday's attack, charges they deny.
TOXIC MIX OF PROXY WARS
The Sunni-Shi'ite faultline in the region, though dating back for centuries, has been dug deep in the last 30 years.
After Iran's Islamic Revolution in 1979, Pakistan's then dictator Muhammad Zia ul-Haq promoted anti-Shi'ite militant groups and hardline Sunni madrasas to contain Iranian influence.
In doing so, Pakistan won funding from Sunni Saudi Arabia, which has long battled Iran for influence in Central Asia and across the Middle East.
The Soviet invasion of Afghanistan at the end of 1979 brought with it U.S. support for mujahideen fighting there, creating a toxic mix of proxy wars and regional rivalries which produced today's Sunni Islamist militant movement.
Islamic madrasas, or religious schools, sprang up along the borders of Pakistan, including in Baluchistan, many of them preaching hardline Sunni Islam in a defensive wall against the spread of Shi'ite influence from Iran.
Jundollah is believed to have been heavily influenced by the sectarian agenda of these madrasas.
"The modus operandi of the latter (Jundollah) borrows much from the terrorism of the Taliban and Al Qaeda," Pakistan's Daily Times wrote in an editorial.
"For instance, the use of suicide-bombing carries the signature of madrasa-based indoctrination even though the Sunni Baloch of Pakistan are strictly secular..." it said.
Jundollah, according to the Norwegian paper, follows Deobandi Islam, a traditionalist school of thought which first emerged in British India in the 19th century.
The Afghan Taliban, created out of the same madrasa system, are also Deobandis, as are most of the Pakistan-based militant groups -- with the exception of Lashkar-e-Taiba, which follows an ideology more akin to al Qaeda's Salafist views.
The sectarian faultline is not the only issue in the region.
Pakistan has long accused India of funding Baluch rebels on its side of the border to offset Pakistani support for militants fighting in Indian Kashmir -- a charge New Delhi denies.
The Afghan Taliban, according to Washington, are also based in the Baluchistan capital Quetta, home to tens of thousands of Afghan refugees who first fled after the Soviet invasion.
And there are fears more fighters might flee to the region as they are driven out by the offensive in South Waziristan.
But the Sunni-Shi'ite divide, nurtured now into a fresh generation of madrasa-educated boys, may prove the most explosive, souring normally good relations between Iran and Pakistan and leaving both facing determined Sunni militant groups for whom suicide bombing is an essential part of jihad. (Editing by Jon Hemming)