The Israeli army has said it had uncovered the biggest Hamas tunnel in the Gaza Strip so far, just a few hundred metres from a key border crossing, AFP reports.

Such was its size that small vehicles would be able to travel within the tunnel, an AFP photographer granted access to it reported.

The underground passage formed part of a wider branching network that stretched for over four kilometres and came within 400 metres of the Erez border crossing, the army said in a statement.

It cost millions of dollars and took years to construct, Israeli forces said, with the project lead by Mohamed Yahya, brother of Hamas chief Yahya Sinwar, who is believed to have masterminded the October 7 attacks.