KABUL (Reuters) - The Taliban in Afghanistan vowed on Saturday to start a new campaign of mass suicide attacks on foreign military bases and diplomatic areas, as well as damaging "insider attacks", as part of a new spring offensive this year.
The offensive was announced via emails from Taliban spokesmen. The Islamist group has made similar announcements in recent years, which have sometimes been followed by spikes in violence after Afghanistan's harsh winter months.
The announcement of more mass suicide and insider attacks will likely be greeted with concern by the NATO-led military coalition, which is in the final stages of a fight against the Taliban-led insurgency that began in late 2001.
However, there was no immediate reaction to the Taliban's statement from the NATO-led International Security Assistance Force (ISAF).
After announcing their spring offensive last year, the Taliban launched a large attack in Kabul involving suicide bombers and an 18-hour firefight targeting Western embassies, ISAF headquarters and the Afghan parliament.
The start of the traditional "fighting season" is particularly important this year, with ISAF increasing the rate at which it hands security responsibility to Afghan forces before the withdrawal of most foreign troops by the end of 2014.
The Taliban statement said this year's offensive, named after Khalid bin Waleed, one of the companions of the Islamic prophet Mohammad, will involve "special military tactics" similar to those carried out previously.
"Collective martyrdom operations on bases of foreign invaders, their diplomatic centers and military airbases will be even further structured while every possible tactic will be utilized in order to detain or inflict heavy casualties on the foreign transgressors," the statement said.
Insider attacks, also known as "green on blue" attacks, involve Afghan police or soldiers turning their guns on their ISAF trainers and counterparts. They have grown considerably since last year and have strained relations between Kabul and foreign forces.
However, there is considerable debate over how many can be attributed to infiltration by insurgents and how many are by disgruntled members of the Afghan security forces.
Last August, then ISAF commander, U.S. General John Allen, said about a quarter of such attacks involved the Taliban.
The spring offensive was coordinated to begin on April 28 to coincide with a national holiday to mark the overthrow of the Soviet-backed government of Mohammad Najibullah in 1992, the statement said.
(This story corrects date of offensive in last paragraph to April 28, not May 28, removes reference to Islamic calendar)
(Reporting by Dylan Welch and Mirwais Harooni; Editing by Paul Tait)