Jewish settlers in the West Bank are conducting a systematic and expanding campaign of violence against Palestinian farmers, families and children with the Israeli authorities turning a blind eye, according to confidential reports from senior European Union officials.

In two reports to Brussels from EU heads of mission in Jerusalem and Ramallah, obtained by the Guardian, the officials found that settler violence against Palestinians has more than tripled in three years to total hundreds of incidents.

"Acts of settler violence are becoming a serious concern for the Israeli state which has so far failed to effectively protect the Palestinian population," says the report sent to EU ambassadors in Brussels last month.

The report notes 411 attacks by settlers last year resulting in Palestinian casualties and damage to property, against 132 attacks in 2009.

The campaign of intimidation is especially targeted at Palestinian farmers and their livelihood, the reports found, noting that settlers damaged or destroyed Palestinian olive groves en masse.

Around 10,000 trees were destroyed last year. But last autumn's olive harvest season was quieter than previous years.

The Israeli authorities are accused of structuring their security operations to minimise the cost to the settlers of the campaign of harassment, intimidation and violence.

"Over 90% of monitored complaints regarding settler violence filed by Palestinians with the Israeli police in recent years have been closed without indictment," the February report says.

A previous and more detailed analysis from April last year described the increasing settler violence as "an alarming phenomenon".

"Discriminatory protections and privileges for settlers compound these abuses and create an environment in which settlers can act with apparent impunity."

The Israeli authorities' failure to resolve 92% of 600 reported incidents by April last year effectively encouraged the settlers to step up the violence, the report argued, adding that the perception had been created that "settler violence enjoys the tacit support of the state of Israel".

The manner in which the Israelis organise security operations in the West Bank militates against the Palestinians enjoying protection.

Children are stoned going to school and Palestinian shepherds and farmers are common targets for violence.

For more than 300,000 Jewish settlers in more than 200 locations in the West Bank, the Israeli military is obliged to intervene if there is retaliatory Palestinian violence. The army, though, is relatively powerless to halt violence against Palestinians since this is the remit of the Israeli police.

"Arguably the single most important deficiency in the provision of an impartial rule of law is the difference in the level of protection afforded to settlers and Palestinians," the report says.

The EU officials say that, according to Israeli security sources, the campaign of violence is being masterminded by around 100 militant settler leaders, and they point to the potential electoral liability for any Israeli government that seeks to get to grips with the violence.

"In Israeli terms, there is a negative political consequence to cracking down on settler violence and no political gain from protecting violence."

Apart from deploring the violence and demanding explanations from the Israeli authorities, the EU officials propose scant other action to halt the campaign.

They suggest to their superiors in Brussels that settler leaders urging violence against Palestinians be blacklisted by the EU and barred from travelling in the union.