Ofcom's report into the purchase said that the acquisition raises public interest concerns about a concentration of power in the market for providing news.
Seperately, Ofcom has published its report into the Channel 4 programme Big Brother and the racism and bullying of Shilpa Shetty alleged to have taken place in the most recent series of Celebrity Big Brother.
The broadcaster must ensure that apologies are read out at the start of the first show of the next series next Wednesday, at the start of the repeat of that show the next day and at the start of the programme in which the first eviction will take place.
Rupert Murdoch's BSkyB purchased its stake in ITV last year as cable company NTL was mounting an attempt to buy the company. NTL had by then merged with Virgin and is now re-branded as Virgin Media.
Virgin and BSkyB are fierce competitors in the UK pay television market, with Sky offering a satellite service and Virgin a cable TV service.
Having examined the reports by the OFT and Ofcom, the DTI and the Secretary of State for Trade and Industry Alistair Darling said that there were issues for the Commission to examine.
The OFT report found that the deal could cause a substantial lessening of competition in the television market and that the issues were too serious to be addressed simply by undertakings from the companies involved.
Ofcom found that the deal raised concerns about the plurality of UK TV news market and in the multimedia news market.
"My decision reflects consideration of the reports I have received from both the Office of Fair Trading and Ofcom and of other representations I have received about this matter," said Darling. "On the basis of the evidence before me, a fuller investigation by the Competition Commission is justified."
