(Adds background, detail on Taliban travel ban lifted)
By James Mackenzie
KABUL, April 12 (Reuters) - Taliban fighters mounted a big attack in eastern Afghanistan on Friday heralding the start of a spring offensive despite ongoing preparations for another round of peace talks.
A Taliban statement said the objective of the Al-Fath ("Victory") offensive was "eradicating occupation, cleansing our Muslim homeland from invasion and corruption, establishing an Islamic system along with defending and serving our believing fellow countrymen".
Hours after the announcement, a large number of Taliban fighters stormed the Shirzad district centre in eastern Nangarhar province, on the border with Pakistan, putting heavy pressure on government forces, local officials said.
Combat had already intensified across Afghanistan in recent weeks and hundreds of Afghan troops and civilians have been killed, making the launch of Al-Fath largely symbolic.
The Afghan government mounted its own offensive, dubbed Khalid, in March.
Friday's clashes took place days before the expected resumption of talks between U.S. peace envoy Zalmay Khalilzad and Taliban officials in Doha.
Representatives from a range of Afghan groups are also expected to be present but the talks will once again exclude the Afghan government, which the Taliban dismiss as a U.S.-appointed "puppet" regime.
International travel restrictions were lifted on members of the Taliban's negotiating team, including its leader Mullah Abdul Ghani Baradar, Taliban spokesman Zabihullah Mujahid said.
However, after repeated rounds of negotiations between U.S. and Taliban representatives over recent months, the new offensive underlined how far Afghanistan remains from peace more than 17 years after U.S.-backed forces drove the Taliban from power in 2001.
"Even as large parts of our homeland have been freed from the enemy yet the foreign occupying forces continue exercising military and political influence in our Islamic country," the Taliban statement said.
Khalilzad condemned the announcement as "reckless" and said: "The Afghan people have clearly voiced a preference for peace."
As well as assurances that civilians would be protected, the Taliban called on Afghan government soldiers and police, who have been suffering thousands of casualties a month, to abandon their posts and join the insurgency.
"We again call on troops working in enemy ranks to shun senseless hostility and futile resistance, to join the Mujahideen and gain guarantees of safeguarding life and wealth," it said.
The Taliban have made gains as moves towards a possible peace deal continued, with government forces in control of just over half the country, according to U.S. estimates.
U.S. President Donald Trump was reported last year to be planning to withdraw about half of the 14,000 U.S. forces in Afghanistan, adding pressure to secure a peace agreement with the Taliban to prevent the country collapsing.
High-profile attacks in cities such as the capital, Kabul, have dropped in recent months, but heavy fighting has carried on in the provinces.
A total of 3,804 civilians were killed last year, the highest number recorded, according to United Nations figures. Afghan security forces have suffered the brunt of losses, with more than 45,000 killed since 2014.
(Additional reporting by Abdul Qadir Sediqi and Ahmad Sultan in Jalalabad Editing by Paul Tait and Angus MacSwan)
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