Labour leader Ed Miliband has paid tribute to European election candidate Del Singh, who died in a devastating suicide attack in Afghanistan.
He was one of two Britons among the dead in the attack in Kabul, which killed at least 21 people.
The Leader of the Opposition said: "My thoughts - and the thoughts of the whole Labour Party - are with the family and friends of Del Singh who was killed in yesterday's tragic suicide bomb in Kabul.
"People everywhere will be appalled and shocked by this barbarous act of terror deliberately targeting members of the international community living and working in Kabul in the service of the Afghan people.
"Del spent over 10 years carrying out vital work on development projects in Afghanistan, Kosovo, Sudan, Sierra Leone and other countries.
"He dedicated his life to working with people across the world who needed his support."
The Foreign Office (FCO) earlier named one of the British nationals killed in the blast as Dhamender Singh Phangurha, understood to be the full name of Mr Singh.
Labour general secretary Iain McNicol said: "Del Singh was a committed and passionate campaigner who wanted to improve the lives of people in conflict zones and those of people closer to home.
"Del will be missed by everyone in the Labour Party who has worked and campaigned alongside him for over two decades. Our thoughts are with his family at this sad time."
The blast occurred at the Taverna du Liban restaurant, which is popular with tourists and westerners.
The suicide attacker detonated his explosives outside the gate of the heavily fortified restaurant, the deputy interior minister Mohammad Ayoub Salangi said.
Two gunmen entered the restaurant and started shooting at people inside. It is believed they were eventually shot dead by security forces when they arrived at the scene.
The restaurant is in an area home to several embassies, non-governmental organisations and the homes and offices of Afghan officials, and like most places frequented by foreign diplomats, aid workers, journalists and businessmen in the war-weary country, has no signs indicating its location and is heavily secured.
It is on a small side street in the diplomatic quarter of the central Wazir Akbar Khan area, just off a bumpy semi-paved road in a house with low ceilings and an enclosed patio, but no windows.