Afghan officials say militants from Iran and Iraq are now joining the insurgency in Afghanistan. The claims come after authorities captured several suspected terrorists allegedly sneaking into the country from neighboring Iran.
Afghanistan's Interior Ministry confirmed the recent arrests on Thursday.
Ministry spokesman Yousuf Stanezai says the men, all suspected militants, were detained earlier this week after illegally crossing the border from Iran.
"The police in Nimruz Province arrested four people. One man was Iraqi, one was Iranian and two were Kashmiri," he said.
The official investigation is still under way but he says the Iraqi was likely headed to southern Afghanistan, where Taleban insurgents maintain a powerful presence.
"According to the preliminary investigation the Iraqi was arrested on the way to Khandahar where he had plans to perform some terrorist activity," he added.
He says all four men had ties with terrorist groups inside Afghanistan.
The charges come amid a sharp rise in suicide bomb attacks across the country.
Once relatively unheard of in Afghanistan, there have been nearly 24 suicide bombings in the past four months.
Wednesday, a suspected Taleban insurgent, dressed as a woman, killed five people in eastern Afghanistan.
Security experts say it appears local militants are increasingly importing tactics used by Iraqi insurgents.
Now local authorities say Iraqi and other foreign militants are themselves joining the fight in Afghanistan.
Officials claim many of the attacks originate in neighboring Pakistan where they believe hundreds of militants have established temporary bases in the semi-autonomous tribal areas along the border.
Pakistan says it has deployed some 80,000 troops to secure the border area and arrest suspected Taleban and al-Qaida fugitives.
Popular resistance to the attacks is also on the rise in towns and cities across Afghanistan. The last few suicide bombings have provoked widespread public demonstrations demanding an end to the militant campaign.
More than 1,000 people joined a protest in southern Afghanistan seeking a more secure border with Pakistan and an end to the recent wave of suicide attacks.