Thousands of people have gathered in Lisbon to attend Europe's largest technology conference, the Web Summit, as the event attempts to get back on its feet after the resignation of its CEO over comments he made about the Israel-Hamas war.

Paddy Cosgrave, the founder of the Web Summit, drew criticism for a post on social media related to Israel's assault on the Gaza Strip in retaliation for Palestinian militant group Hamas' attack on October 7, saying "war crimes are war crimes even when committed by allies".

Several leading tech companies, namely Google, Meta and Siemens, as well as various speakers said they would not attend the event in response to Cosgrave's post.

Cosgrave resigned as CEO last month, saying his personal comments on the conflict had become a distraction from Web Summit 2023 in Lisbon.

Web Summit appointed former Wikimedia Foundation CEO Katherine Maher as the chief executive.

"I think it's important to say that I believe everyone, everywhere, has the right to express their views on what is happening in the world," Maher said as she addressed Cosgrave's resignation at the event's opening.

Web Summit CEO Katherine Maher

"But having a right to expression, and considering the weight of your words are two different things," she said.

Most of the attendees who spoke to Reuters said the controversy would not have an impact on their experience and praised the new CEO for addressing the issue straight on.

The Web Summit said more than 300 of its partners were coming to the event and that some "who were deliberating have come back on board and reversed their decision".

A record-breaking 2,600 startups and more than 900 investors were expected to attend.

The event attracts about 70,000 participants every year, drawing speakers from global tech companies and startups, as well as politicians.

Some of this year's high-level speakers include former US army analyst and WikiLeaks source Chelsea Manning and Alibaba.com president Kuo Zhang.