Will Lewis told the 6th Newsroom Summit, staged by newspaper technology support agency Ifra in Paris: "Our ability to protect that content is under consistent attack from those such as Google and Yahoo who wish to access it for free.
"These companies are seeking to build a business model on the back of our own investment without recognition. All media companies need to be on guard for this.
"Success in the digital age, as we have seen in our own company, is going to require massive investment - [this needs] effective legal protection for our content, in such a way that allows us to invest for the future."
Google News, which uses a computer algorithm to automatically scrape and aggregate story summaries from thousands of publishers, has occasionally fallen foul of copyright complaints.
Although some publishers regard exposure in such gateways a benefit, Associated New Media previously called search sites "parasites", while a Belgian court recently ordered the site to stop aggregating newspaper content.
Google and Agence France Presse this month settled a two-year legal dispute over the same issue, without disclosing whether the search giant will limit its actions or pay the agency for stories.
Mr Lewis, who said he was reading Telegraph Group CEO Murdoch Maclellan's speech in absentia, also called for "reforms of the laws of liberty" to protect freedom of expression, complaining that any new media expression laws passed on statute would be "unenforceable".
The summit also heard how one small US newspaper, the Shelby Star in a town of just 27,000 people, had increased its web traffic by 84 per cent after being selected to pioneer new methods in online storytelling including video and moblogging.
And Talkshow Communications director Jonathan Halls, a former manager of BBC new media skills, said BBC director general Mark Thompson's "vision clarity" had "failed" because staff are preoccupied with the threat of redundancies rather than Mr Thompson's ambitious plans to help the corporation compete in the new media age.
Free daily newsletter
- “Hey Google, tell me something good”
- Google is giving $6.5 million to fact-checkers focusing on coronavirus
- Data crunching, weekly formats and vertical accounts: behind The Telegraph's Instagram strategy
- Half of publishers bet on reader revenue as their main income stream in 2020
- What will the next decade look like for journalism?