International observers of Zambia's elections said Saturday the poll was marred by claims of intimidation, abductions and an hours-long pause in the vote count.

Observer missions called for parties to tone down inflammatory statements as the votes cast on Thursday were tallied, and some teams extended their deployment because of the tensions.

President Hakainde Hichilema, 64, is seeking a second term. His main challenger is a 55-year-old former minister in the previous Patriotic Front (PF) government, Brian Mundubile.

The electoral commission suspended vote counting for around six hours on Friday following reports of violence against polling staff and the alleged theft of ballot papers.

The count resumed after the commission announced the "security threat" had been contained.

The suspension of the count had caused "uncertainty and anxiety", said the observer mission of the regional SADC grouping, led by Samuel Tembenu, a former Malawian justice minister.

"The mission additionally recorded, but could not verify, reports of intimidation, assault, abduction and damage to property in five provinces, some involving reported physical injury and, in one submission, fatalities," said Tembenu.

Police said nine suspects had been arrested after the killing of a 57-year-old polling agent in a township outside Lusaka on voting day, although they added that the election had generally been peaceful.

"Even one loss of life is one too many," said Reinhold Lopatka, head of the European Parliament's election observers' delegation.

The suspension of counting appeared "disproportionate" as only a small number of the more than 13,000 polling stations had reportedly been compromised, the Austrian politician told reporters.

The mission had been informed that "opposition parties faced intimidation, including by security forces, candidates reportedly withdrawn under pressure, and opposition rallies were ended by violence," he said.

- 'Confidence of voters' -

The election commission started releasing constituency results late Friday, pledging the final outcome would be made public by Monday.

The suspension of counting risked "the credibility of the process and the confidence of voters", said Botswana's former president Mokgweetsi Masisi.

His International Conference on the Great Lakes Region (ICGLR) observer mission had urged the main parties "to de-escalate, to refrain from announcement of any results, to stop any inflammatory language (and) reassure us that they will continue respecting the rule of law", he said.

The elections took place "against a backdrop of constrained democratic space", said Michael McNamara, chief observer of the European Union mission.

"Advantages of incumbency and the blurring of lines between state and party contributed to an uneven playing field," he told reporters.

The EU observers "found state-owned media coverage to be heavily biased in favour of the ruling party."

McNamara said the EU had met with the opposition, government and even the chief justice to stress that any challenges to the vote outcome should be handled "peacefully".

"Disaggregated results data at polling station level should be made available nationally as this would increase people's trust in the process," he said.

Some 8.7 million voters were registered in the copper-rich nation of 22 million, which has a long record of peaceful transfers of power.

The election is seen as a test of Hichilema's first five years in office, during which the economy returned to growth although critics say this has yet to translate into better living standards for ordinary households.

His government also faces charges of narrowing the space for dissent.

More than 70 percent of Zambia's 22 million people live on less than three dollars a day, according to World Bank data.