Zambia on Wednesday postponed parliamentary by-elections that have sparked bloodshed in the tourist town of Livingstone, as President Michael Sata urged citizens to stop killing each other.

"Due to unprecedented levels of intolerance by political parties and violence" the vote in the southern town has been postponed from Thursday to March 14, said Zambia's electoral commission chief Irene Mambilima.

The current political environment in Livingstone "is not conducive to hold free and fair elections," she added.

Campaigning for the by-elections in two parliamentary constituencies has been marred by unrest that has led to the death of a ruling party member, prompting Sata to appeal for calm earlier on Wednesday.

"Why are you fighting? Stop fighting and stop killing each other, your blood is the same," Sata said. "We are the same people and so you should stop killing each other."

The announcement of the vote postponement came as the leader of the country's second-largest opposition party was freed on bail in connection with the killing of Harrison Chanda, a party youth secretary who police say was hit on the head with an axe after being attacked by a group of people in Livingstone on Monday night.

Hakainde Hichilema of the United Party for National Development (UPND) has been charged with inciting violence and was granted bail after a court ordered him to pay a bond of 2 000 kwacha ($370). He is to return to court on May 28.

Two lawmakers and 23 other opposition members still remain in police custody over Chanda's death, the party said.

The arrest of 26 opposition members "is unacceptable, barbaric and not good for our democracy," UPND spokesman Cornelius Mweetwa told AFP.