Opposition presidential challenger Michael Sata's party claimed he was ahead in the vote count from Tuesday's election, but news agencies reported that the poll was too close to call.

The Zambian news site The Post Online said Sata had done well in his urban strongholds of Lusaka and the towns of the Copperbelt, but had also improved his showing in President Rupiah Banda's expected stronghold in the Eastern Province.

Radio station Q-FM reported Sata's Patriotic Front as announcing that preliminary figures showed Sata leading with 56 percent of the vote, against Banda's 32 percent.

But Agence France-Presse noted that the returns were too small to give any indication of the final result, and Zambia's state broadcaster carried a warning from the Electoral Commission of Zambia that media houses should not anticipate official results.

The Post quoted Sata as saying: "This is my election. And because it is my election, there is no way that the Patriotic Front and myself, in particular, can lose. This election is ours and nobody will take that away from me and the PF in general."

Banda's Movement for Multiparty Democracy has been in power for 20 years.