“Whoever dares to campaign will be responsible for what happens,” Yala warned, without elaborating.
He earlier denounced “massive fraud” in the first round on March 18 and said: “I have said and repeat it. I do not want a second round.”
Gomes garnered 48.9 percent of the votes on Sunday last week and Yala 23.26 percent. The election campaign for the second round was supposed to start yesterday and end on April 27.
Since winning independence through armed combat in 1974, Guinea-Bissau’s army and state have remained in constant, often deadly conflict, with the result that no president has ever completed a full term in office.
Three have been overthrown and one was assassinated in office in 2009.
The latest election was held after former Bissau-Guinean president Malam Bacai Sanha died in January following a long illness.
The UN Security Council last Saturday urged Guinea-Bissau candidates and voters to “exercise restraint” ahead of the presidential run-off.
The 15-member council urged the country’s political leaders to “resolve their disputes in accordance with the constitutional framework.”
They underscored the importance of successful elections to progress on peace-building priorities including demobilizing troops and police, fighting drug trafficking and promoting national reconciliation.