Kenya opposition leader Raila Odinga said the ruling party cannot win next week's national elections unless it rigs the result.

"There is no other way that Jubilee can win elections other than through rigging and they know it - that is why they are making all the efforts," he told Reuters as he left an election rally in the town of Susan near the capital.

"I'm very confident that we are going to get a very, very decisive victory," he said.

A veteran opposition leader, Odinga is running against incumbent President Uhuru Kenyatta in next week's Aug. 8 polls, when Kenyans will choose a new president, lawmakers and local representatives.

Many voters are jittery, fearing a repeat of the 2007 polls, when Odinga alleged rigging and called for demonstrations. The political protests and ethnic violence that followed killed more than 1,200 people.

During the next polls, in 2013, Odinga also lost and called foul, but he took his concerns to court and the elections were largely peaceful.