Khartoum - A two-day-old ceasefire in South Sudan is still not firmly in place, the foreign minister of Norway, part of the so-called Troika with Britain and the United States, said on Sunday.
"We see a very shaky ceasefire", Foreign Minister Borge Brende told AFP in an interview in the Sudanese capital.
His comments, after talks with Sudanese officials, came as the South's government and rebels traded accusations that each had breached the ceasefire deal by attacking the other.
"Of course I'm concerned and I think what this means is we also have to establish the right monitoring tools and also verification tools so one can really assess" the extent of compliance, Brende said.
The Troika helped oversee implementation of a 2005 peace agreement which ended Sudan's 22-year civil war and ultimately led to the South's independence in 2011.
Since then, the Troika have continued working together supporting peace and development in Sudan and South Sudan, including through backing a regional-led initiative to end weeks of fighting.
Forces loyal to South Sudan President Salva Kiir have battled a loose coalition of army defectors and ethnic militia nominally headed by sacked vice president Riek Machar.
The seven-member East African regional bloc IGAD, which includes Sudan, mediated talks in Ethiopia between South Sudan's two warring sides.