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.
The FCO has confirmed the name of the other Briton killed in the attack as Simon Chase.
Mr Chase, a former British soldier, was originally from Merseyside but had been living in Limavady, Co Londonderry with his fiancee Norma McDowell.
The healthcare worker from Limavady was today being comforted by family and friends. It is understood the couple lived together with two children in the Drumachose Park area of the town.
The ex-Cheshire Regiment soldier had worked as a nightclub doorman in Limavady before travelling to Kabul to work in the security industry.
Mayor of Limavady Gerry Mullan extended his condolences to Mr Chase's family.
"There is cloud that has descended upon the local community who are very shocked and saddened by his loss," said the SDLP councillor.
"He was a well-known and well-respected figure in the community."
Limavady Democratic Unionist councillor Alan Robinson said there had been an outpouring of grief for a man who was well liked and admired for the work he did.
"People greatly admired him being away from home in foreign parts doing dangerous work many of the rest of us wouldn't consider doing," he said.
Mr Singh, who previously worked for the executive office of the Deputy Prime Minister, was working as an international adviser supporting the Afghan Budget Department in Kabul at the time of the blast.
Colleagues have paid tribute to a "professional, reliable and witty" character who was a pro-Palestine supporter.
William Morrison, m anaging director of Adam Smith International, said: " Del was skilled at drawing people together - his presence made meetings flow more smoothly, and helped difficult negotiations reach amicable conclusions.
"His professionalism, reliability, and irrepressible good humour made him well-known throughout the Budget Department and the close international community in Kabul. Del was the sort of person who was always welcome in any room or any discussion - it was impossible to be bored or out-of-sorts when Del was around.
"His constant stream of witty remarks and clever jokes could make anyone laugh. But his levity could only partly mask his deep commitment to the work he had chosen, including his lifelong dedication to the Palestinian cause, for which he spent much of his spare time doing volunteer work."
Mr Singh's colleague, Malaysian advisor Gnana Nagarajah, was also killed in the incident.
He was described as possessing a "razor-sharp mind, deep experience, and kind-heartedness".
Mr Morrison said: "It was impossible not to love him - for his generosity, which delighted in giving gifts to others and cooking elaborate meals for his friends; for his caring nature, which made him the sort of person who thought the best of everyone and always looked out for the welfare of others; and for his gregariousness, which led him to host parties and surround himself with friends.
"Gnana and Del had this in common: they were an unqualified pleasure to work with, to live with, and to spend time with. It was a profound privilege to have known and befriended them - their death is an enormous loss. We express our deepest condolences to their families and all our thoughts are with them at this terrible time."