Zambia will hold presidential and parliamentary elections on August 11 under a new constitution, a government spokesman has said.

President Edgar Lungu is expected to assent to the constitutional amendments on Tuesday, ratifying the election date, his spokesman Amos Chanda said on Monday.

"The new constitution has a fixed election date and that will take effect as soon as the president signs," Chanda told Reuters.

The elections are expected to be a tight contest between Lungu's ruling Patriotic Front (PF) party and Hakainde Hichilema's opposition United Party for National Development (UPND).

Confident of victory

Under the previous constitution, the president set the election date every five years. Presidential candidates will run on a joint ticket with a vice-presidential candidate, unlike the current arrangement where the president appoints his deputy, Chanda said.

Other amendments include a clause requiring a winning presidential candidate to win more than 50 percent of the valid votes cast, he said.

On Sunday, President Lunga said that he was confident that Zambians were firmly behind him. The incumbent said he expected to secure at least 71 percent of the ballot in August.

Presidential elections were previously held in Zambia in January 2015 to elect a president to serve out the remainder of the term of President Michael Sata, following his death on October 28, 2014. Lungu narrowly won the election with 48.3 percent of the vote, with Hichilema close behind with 46.6 percent.

Source: Agencies