The ICO previously dropped a probe into the affair after being told that only limited data had been "mistakenly collected" by the project.
An audit by the regulator also revealed that Google had made improvements to its privacy structure and policies, and given assurances that such a situation would not happen again.
But the ICO has today (June 13) said that it will reopen the investigation after more information on the Street View beaches was released by the US Federal Communications Committee (FCC) in April.
The FCC found that the software to harvest payload data from unsecured home wireless networks was deliberately written by a Google engineer in 2006.
The engineer, not named but understood to be Marius Milner, had created special software that could "collect, store and review payload data for possible use in other Google projects".
In a letter sent to Alan Eustace, a senior vice president at Google, the ICO confirmed that it had reviewed the FCC report and now wants more information from Google.
Steve Eckersley, the senior enforcement officer at the ICO, told Eustace that the FCC appears to have found that a "wide range" of data was gathered by Street View cars as they travelled around capturing images of the US.
This includes IP addresses, complete email messages, login details, medical listings, legal infractions, video files and web histories, including "online dating and visits to pornographic websites".
"It therefore seems likely that such information was deliberately captured by GSV (Google Street View) operations conducted in the UK," said Eckersley in the letter, which was copied to Google's privacy counsel Peter Fleisher.
"However, during the course of [initial] investigation we were specifically told by Google that it was a simple mistake [but] if the data was collected deliberately then it is clear that this is a different situation than was reported to us in April 2010.
"Given the findings of the FCC we have reopened our investigation."
> Google fined $25,000 for impeding US Street View investigation
> Google facing new WiFi snooping investigation in UK
The ICO now wants additional information from Google, including a full list of the types of personal and sensitive payload data that were harvested from unsecured WiFi networks in the UK.
It wants to know at what point Google managers learned about the breach in the UK, and what action was taken to deal with the issue.
Google must also explain why it did not include samples of the stolen data in its original submission to the ICO's first Street View investigation.
In response, a spokesman for Google said: "We're happy to answer the ICO's questions. We have always said that the project leaders did not want and did not use this payload data. Indeed, they never even looked at it."
Privacy group Big Brother Watch welcomed the ICO's reopening of the investigation into Street View.
"The investigation must now be pursued with the vigour sadly lacking in 2010, and every effort made to ensure that Google answers the extremely important questions that it has so far avoided," said Nick Pickles, director of the group.
"Breaching the Data Protection Act is a criminal offence and the law should be applied to Google in the same way as any other company or individual."