European Union privacy regulators are urging Google to make changes in the way it executes goes about its controversial Street View program, adding to its legal worries in Europe.

Authorities are pushing the US Internet giant to shorten the period it stores images due to privacy concerns, it said in a letter to the company.

The EU is also asking Google to notify people before it sends its camera vehicles into the streets.

Google rejected the calls, however, saying its need to retain Street View images for one year is legitimate and justified.

Launched in 2007, Street View allows users to navigate around a 360-degree view of city streets, buildings, traffic and people, using pictures taken by Google's camera vehicles. It is currently available in over 100 cities around the world.

Critics accuse Google of failing to obscure sensitive images and setting its cameras in a way that allows them to peer over fences, hedges and walls into private property.

The Working Party believes that a maximum retention of six months for the unblurred copies of the images would strike the right balance between the protection of privacy and the ability to eliminate false positives, the letter, which has a February 11 dateline, said.

The Working Party is made up of privacy supervisors from European Union countries and advises the European Commission on data protection rules.

European countries have been resistant to Google Street View's entry over privacy concerns.

Germany asked the company to erase footage of faces, license plate numbers and house numbers from the service.

Last year Greece asked Google to halt it's plans to enter the country until more safeguards were in place.