South Sudanese President Salva Kiir began Wednesday a two-day visit to Sudan aimed at resolving border disputes and addressing mutual accusations of supporting rebels in each other's territory.
It is Kiir's third visit to Khartoum since the Christian majority south split from the Muslim north in 2011 after a 22-year civil war that killed hundreds of thousands.
Kiir was received by his Sudanese counterpart President Omar al-Bashir at Khartoum airport.
"This visit is aimed at normalising the relations between the two countries which have been tense," South Sudanese Information Minister Michael Makuei told reporters, adding the two leaders will decide on a roadmap to improve bilateral ties.
"The two countries should cooperate in the interests of their people as they are all one people in two countries."
His Sudanese counterpart Ahmed Bilal said the visit aims to "establish security and stability in the two countries".
Officials say Kiir will hold talks with Bashir and other senior Sudanese officials to thrash out several unresolved issues between the two countries.
Border rows, economic issues such as Juba's payments for the use of an oil export pipeline through Sudan and building a buffer zone along the frontier are among the expected topics of discussion.
Officials will also attempt to address tensions over alleged support for insurgents.
Sudan has regularly accused its neighbour of aiding rebels in its war-torn Darfur, Blue Nile and South Kordofan regions.
Juba has often accused Khartoum of aiding Kiir's opponent and former deputy Riek Machar in South Sudan's ongoing civil war.
Tens of thousands of people have died in South Sudan and millions more have been driven from their homes since the war erupted in the world's youngest country in December 2013.
More than 450,000 South Sudanese refugees have poured into Sudan since the war broke out, the United Nations says. Khartoum estimates they number 1.3 million.
Juba said it appreciates Khartoum's efforts to accept the growing number of refugees.
Apart from helping the refugees to enter Sudan, the recent openings of border crossings by Khartoum has also helped trading activities between the two neighbours, Juba said in a statement issued on Wednesday before Kiir left for Sudan.
"South Sudan will do all it can to ensure that the Republic of Sudan interests in South Sudan are protected and promoted," it said.
Several senior South Sudanese officials have regularly visited Khartoum while Kiir himself previously visited in 2015.
A South Sudanese delegation of senior officials had already arrived in Khartoum a few days earlier for preliminary meetings ahead of Kiir's arrival.