The Cern physics laboratory near Geneva appeared to leak crucial details of its hunt for the long-sought Higgs boson particle on Tuesday when it accidentally posted a video announcing the discovery of a new particle on its website.

Senior scientists at Cern are due to reveal the latest findings in the hunt for the famed particle at a much-anticipated press conference in Geneva on Wednesday, and had tried to keep the results under wraps, despite intense rumours that the laboratory had found the particle.

But Cern, which takes credit for inventing the world wide web, inadvertently released a video interview on its website dated 4 July 2012 in which spokesman Joe Incandela states the lab has “observed a new particle”.

A press officer at the laboratory blamed a technical glitch for the video going live. The interview was taken down shortly after.

Speaking on the video, Incandela stopped short of claiming the particle was the Higgs boson, saying more work was needed to be sure. “We have quite strong evidence that there’s something there. It’s properties are still going to take us a little bit of time,” he said.

The details Incandela revealed suggest it has the hallmarks of the Higgs particle. “We can see that it decays into two photons, for example, which tells us it’s a boson, it’s a particle with integer spin, and we know its mass is roughly 100 times the mass of the proton. And this is very significant.

“This is the most massive such particle that exists, if we confirm all this, which I think we will,” he said.

“It’s something that may, in the end, be one of the biggest observations of any new phenomena in our field in the last 30 or 40 years, going way back to the discovery of quarks,” he added.

A spokesperson for Cern said the video went live on the internet due to a “technical fault”. They added that the lab had recorded several videos in advance with spokespersons at the lab.