Three days of mourning
Justin Yak, a presidential advisor on decentralisation, and his wife were also killed in the crash which was in the remote Bahr al-Gazal region.
Salva Kiir, the leader of south Sudan, has cancelled a plan to visit Oslo, Norway, for a conference next week in order that he can attend the victims' funerals.
Kiir described the crash as "one of the saddest'' the region has witnessed and declared three days of mourning in the south, with flags on government buildings to be flown at half mast.
Hamid Ghallab, an SPLM leader, said on Saturday that the SPLM general congress on May 10 in Juba will not be postponed. Dim's successor will be elected at the conference.
A 2005 peace agreement between north and south Sudan is currently being tentatively implemented by their respective governments.
The deal ended a 22-year long civil war between the two sides.
Chan said: "Although the loss is so great, it will never deter us from the
implementation of the peace agreement."
The charter aircraft had been taking a delegation of leaders from the SPLM from Way to Juba.
The airplane's captain had called the airport tower to report engine trouble and request an emergency landing, the Sudanese Civil Aviation Authority said.
An official investigative committee has yet to be formed for Friday's disaster which killed three crew members and 21 passengers.
Many of Sudan's airplane crashes occur due to old and unsafe aircrafts being used - what one local columnist called "flying coffins" on Saturday.