Hood was speaking at the World Publishing Expo in Berlin, in which he delivered a presentation on "the importance of preventing data leakage".
"If it leaks, third-parties can make money – money which we should be getting," he explained, a point echoed in a presentation at the conference by News Corp's Raju Narisetti.
News sites are often asked to add code to a website when they add a new feature. This code can include cookies, small text files placed onto a user's computer which can track browsing habits.
"The say 'if you put this bit of code into your site, we will give you an easy-to-use analytics system or comments platform'," Hood told the conference.
"But that means they have access our audience data," he explained.
"Advertisers have more insight into audiences than publishers. And that’s what we’ve got to stop," he said, urging publishers to "stop hemorrhaging data".
Hood recommended to conference delegates that they take a look at the code from external platforms added to their news sites. "We need to be thoughtful and do tag audits," he said.
Publishers "can invent more native ad formats which cannot be bought and sold", he said, such as homepage takeovers.
He explained how Archant, which owns four daily newspapers, around 50 weeklies, 80 regional and lifestyle magazines and 200 websites, blocked the data leaks a year ago. It started using a tool called Cxense, which "extracts meaningful audience insights", he said.
A few months after implementing the block on leaks, an increasing number of advertisers started contacting the news sites in the group directly, Hood added.
Digital advertising and the challenge for publishers
On a separate note, Hood also warned delegates about competition in digital advertising. Yahoo, Google and Facebook, for example, make up 50 per cent of spend for online display advertising, he told the conference.
Google is now taking 60 per cent of total internet advertising spend, mainly through search, he said, explaining forecasts predict that over the next three years Twitter is likely to account for 4 per cent of the online ad market.
The marketplace for display advertising "is extremely complex", Hood said, and "is absolutely full of players many of us have never heard of".