The bodies of five volunteers working for a female MP have been found riddled with bullets in western Afghanistan, amid a growing campaign of violent intimidation against women running in the country's elections.

The men, aged between 20 and 35, were found dead by villagers in the Adraskan district of Herat province, some distance from where they were kidnapped by gunmen on Thursday while out campaigning for Fauzia Gilani.

The Taliban claimed responsibility for the kidnapping of 10 of her campaign workers as they travelled in remote countryside. Five of the workers were released before the others were found dead.

The insurgent movement has not yet claimed responsibility for the murders, but Gilani – one of hundreds of women running in next month's elections – said she believed the "enemies of Afghanistan" were responsible.

"These people were just my volunteers," she said. "They were just trying to help – I wasn't paying them any money."

She said she did not know whether they were targeted because she is a woman, but said that in western Afghanistan, the "society is controlled by men".

"They are in charge, and they don't want a woman to be above them," she said.

The politician struggled to speak when the Guardian contacted her by phone. She said she was standing next to the bodies of the victims at an Afghan national army base, where they were awaiting collection by their families.

One of the defining features of the campaign has been the attacks and scare tactics directed at women contesting seats nationwide. According to a recent survey of violence and irregularities in Logar province, conducted by the Free and Fair Election Foundation of Afghanistan (FEFA), nine out of 10 threats against specific candidates were directed at women.

In other provinces, women have been "inundated" with threatening phone calls, often delivered late at night by insurgents and political opponents. Ahmad Nader Nadery, director of FEFA, said his organisation's research showed that violence in the run-up to polling was far higher across the country than in last year's presidential election, where widespread insecurity was an essential precondition for extraordinary amounts of voting fraud.

In Herat yesterday, gunmen killed a candidate named as Haji Abdul Manan as he walked from his home to a mosque. "This is an environment of high amounts of intimidation and threats to candidates in general, but specifically to female candidates," Nadery said. "We expect more of this, with an increase in attacks on candidates, as we get closer to the elections."

Nadery said the type of people trying to disrupt women's campaigns varied around the country. "It is very dominant in the south by the Taliban, but it also exists in the north of the country where powerful political figures and warlords are responsible," he said.

Fuazia Kufi, an outspoken women's rights activist and one of Afghanistan's best-known representatives, said the increased interest in politics among women had disconcerted traditional power-brokers.

The minister, from Badakhshan, a relatively liberal province in the north, said: "As women get stronger and they find a voice among the public, there are many people who lose power. There are many traditional people who lose so they try to create problems and trouble."

The murder of Gilani's volunteers proved the need for greater government protection of women in politics, she said. "Fauzia Gilani is a very low-profile MP, so if she is being attacked you can imagine how much more difficult it is for the more outspoken candidates. Although the public is really supporting female candidates, there are certain mullahs who deliver the message not to vote for women. This is even happening in a more open province like Badakshan."

The UN mission in Afghanistan said the killings of Haji Abdul Manan and Gilani's volunteers were "unacceptable", and said those responsible must be brought to justice. "These killings constitute violent intimidation of all electoral candidates and their supporters. This is unacceptable. [The UN] calls upon the Afghan security forces to be on heightened vigilance over the coming weeks leading to the parliamentary elections."