US President Barack Obama called the killing of Rabbani a tragic loss but said work needed to continue to bring elements of Afghan society together to end years of violence.
UK Foreign Secretary William Hague said the assassination of former Afghan president Burhanuddin Rabbani will not hurt Afghanistan's bid for peace and reconciliation.
Pakistan's Prime Minister Yusuf Reza Gilani and President Asif Ali Zardari condemned the assassination. They conveyed their 'extreme anger and shock' to the Afghan government over the killing, according to a statement released by the Pakistan government.
UN Secretary-General Ban Ki-moon condemned the attacks and stressed that 'the United Nations remains committed to supporting Afghanistan and its people.'
In Kabul, hundreds gathered on the blocked-off street around Rabbani's home and armoured cars with blacked-out windows carried senior officials, friends and other prominent Afghans to a memorial service inside.
Rabbani, president during Afghanistan's 1992 - 1996 civil war and a warlord with a chequered human rights record, was killed at home Tuesday by a bomber thought to be a trusted emissary bringing a special message from the Taliban.
Rabbani's killing was the most high-profile political assassination since the 2001 US-led invasion dislodged the Taliban.
Rabbani led the High Peace Council which Karzai established last year and charged with establishing contacts with insurgents.
