The UN was worried on Tuesday about the " striking deterioration " of the situation in Afghanistan, where the conflict claimed 380 civilian lives in April, despite the fragile peace process under way.
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The United States and the Afghan Taliban signed an agreement in February in Doha which should pave the way for the withdrawal of American troops from Afghanistan and for peace negotiations between the Islamist insurgents and the government in Kabul.
Civilian casualties attributed to the Taliban increased by a quarter last month to 208 from the same period a year ago, while casualties from operations by Afghan security forces jumped 38 % to 172, according to preliminary data from the United Nations Assistance Mission in Afghanistan (Manua).
" I am calling for a cessation of the fighting and urging the parties to respect the humanitarian law which is there to protect civilians, " urged Deborah Lyons, the special representative of the United Nations secretary-general for Afghanistan.
The United States sent an emissary to Doha and Kabul on Sunday to call on the Afghan government and the Taliban to initiate peace talks that have been blocked since April. Washington hopes that the power-sharing agreement signed on Sunday by Afghan President Ashraf Ghani and his rival Abdullah Abdullah will allow the inter-Afghan peace talks to begin in earnest.