Abu Dhabi (Online): Five diplomats from the United Arab Emirates (UAE) among 50 were dead in an explosion in the southern Afghan city of Kandahar , the Emirates´ official news agency confirmed on Wednesday.

The news agency said that the officials were on a mission to carry out humanitarian, educational and development projects.

It further stated that UAE President Sheikh Khalifa bin Zayed Al Nahyan ordered three days of mourning in honour of the martyrs who gave their lives in defence of humanitarian causes.

The blast was one of a string of bombings that hit three Afghan cities on Tuesday which struck the provincial governor´s office during a visit by the UAE delegation. At least 50 people were killed and over 100 were injured in the explosion .

The carnage underscores growing insecurity in Afghanistan, where US-backed forces are struggling to combat a resilient Taliban insurgency as well as Al-Qaeda and Islamic State militants.

Provincial police Chief Abdul Raziq told media that Kandahar´s governor and UAE envoy Juma Mohammed Abdullah Al Kaabi were injured by flames from the explosion , but many others were burned beyond recognition.

He said a dozen people were killed and an equal number wounded. No militant group has so far claimed responsibility.

Taliban insurgents have escalated their campaign of violence in Afghanistan in recent days, even as winter takes hold.

The assault on the UAE delegation was unusual. In the past the Emirates have had good relations with the Taliban.

When the militant group held power in Kabul between 1996 and 2001, Abu Dhabi was one of just three governments that recognised it.