The blast struck in Chora district of Uruzgan province yesterday when the Afghan employees of the Mine Detection Center (MDC) were travelling to work.
"Two mine clearers were killed and two were wounded in the roadside bomb," Mohammad Gula, deputy provincial police chief, told AFP.
MDC is a non-governmental organisation established in 1989 to sweep landmines mostly planted during the Soviet occupation of Afghanistan.
A Taliban spokesman, Zabihullah Mujahid, claimed responsibility for the blast and said they were targeting a military vehicle.
Also today, a NATO helicopter made an emergency landing due to technical problems in northern Kunduz province, but no casualties were reported, district chief Shaikh Saadi said. NATO did not immediately comment on the incident.
There are currently about 120,000 troops under NATO and US command in Afghanistan battling a Taliban-led insurgency now in its ninth year, with troops numbers expected to swell to 150,000 within months.