Reports of racial and religiously motivated crime rose following the election of British National party councillors in several far- right strongholds, police statistics have revealed.

Complaints of hate crime increased in wards in the West Midlands, London and Essex after the election of a BNP member, in spite of declines in reported hate crime in the wider police areas. In other wards race crime reportedly rose in the runup to BNP election victories, according to the figures, obtained by the Guardian under the Freedom of Information Act.

The findings came as the party stepped up its campaign to win its first seats in the House of Commons with a "weekend of action" in Barking and Dagenham, where the culture and tourism minister, Margaret Hodge, faces a challenge for her Labour seat from BNP leader, Nick Griffin. Hodge said the new figures cast doubt on police assurances that there is no link between racially motivated crime and a BNP presence.

Yesterday, BNP member Terence Gavan was jailed for 11 years after police found nail bombs and 12 firearms at his home in the borough of Kirklees, West Yorkshire, where the BNP has councillors. The Old Bailey heard that Gavan harboured "a strong hostility" towards immigrants.

One of the biggest increases in hate crime came in Barking's Eastbury ward, where racially motivated violence, theft and criminal damage more than doubled in the year after Jeffrey Steed won a council seat for the BNP in May 2006. A year later, hate crime rose again and 45 racial incidents were reported in 12 months.

In several other BNP wards, race crime fell in line with declines in the wider areas, but anti-fascist campaigners believe rises may be linked to BNP election wins. "Voters have been emboldened in their racist views by seeing the BNP in power and that could have led to the increases in racist attacks in some areas," said Sam Tarry, campaign organiser for the Hope Not Hate campaign, set up by the anti-fascist group Searchlight.

"The figures suggest that if the BNP wins more seats, people from ethnic minority and gay communities could face greater persecution because racist and bigoted views will have been further legitimised."

The BNP denies that increases in hate crime are related to its activities and blames the rises on increased immigration. Bob Bailey, the party's London organiser said: "This is due to an increase in the ethnic [sic] population. There are more people who are prepared to go to the police complaining they are victims."

The Guardian has analysed data from 11 police forces covering 29 wards across England where voters have elected BNP councillors in the past six years. In eight wards reports of hate crime rose following BNP election wins despite a wider decline across the police force area. It declined in 14 wards, in line with force-wide reductions, and there was no change in four and an insignificant amount of data in three.

In Essex, complaints of race crime rose after the election of BNP councillors in parts of Epping Forest, while in Chelmsley Wood, a suburb of Birmingham, the ­average annual incidence of race crime almost doubled after George Morgan won a seat for the BNP in May 2006.

In the four years before his election, there were an average 11 incidents a year rising to an average of 21 a year in the following four years. West Midlands police said some cases involved assault, while most were incidents of verbal abuse in shopping centres, taxis and in the police station with white and Asian victims.

Detective Chief Inspector Sharon Goosen said: "None of the offences reported in the area since 2006 can be directly attributed to an elected member or political organisation."

The BNP is understood to be planning to field more than 1,000 candidates in local elections and 300 candidates in the general election. Griffin and the BNP deputy chairman, Simon Darby, who is standing for Stoke Central, are considered to have the best chance of winning seats at Westminster.

Additional reporting: Holly Bentley