Anti-tank missiles were among the weapons smuggled, Mr Diskin said
The flow of explosives and weapons smuggled into Gaza has continued since Israel's military operation, a senior Israeli intelligence official has said.
Shin Bet security service head Yuval Diskin said 22 tonnes of explosives, dozens of rockets and hundreds of mortar rounds had entered Gaza.
But he said rockets attacks were reduced and Egyptian attempts to combat the smuggling had improved.
Israel said the offensive aimed to cut down Palestinian rocket attacks.
In his briefing to the cabinet on Sunday, Mr Diskin also noted a drop in the number of rockets fired into Israel in recent weeks.
He said Hamas, which controls Gaza, was carrying out arrests of members of smaller militant factions to stop attacks, and had signed an agreement with the Islamic Jihad group to end attacks.
Among the items smuggled through tunnels under the border with Egypt in recent weeks, were also 45 tonnes of raw materials for the production of weapons, hundreds of mortar shells and dozens of anti-tank and anti-aircraft missiles, he said.
The tunnels are also used for smuggling in goods that cannot enter Gaza under Israel's blockade of the strip, which allows only humanitarian basics in through the crossings from Israel.
Halting weapons smuggling was a key Israeli demand in the ceasefire deal Israel and Hamas initially sought to negotiate in the wake of the operation.
Attempts to reach a deal which would secure the border and ease the blockade have faltered, although the two sides have largely held to the unilateral ceasefires announced to end the 22-day January conflict.
But Israel has pressured the US, EU and Egypt to step up attempts to combat the smuggling.
Last week outgoing Prime Minister Ehud Olmert made comments widely seen as tacit confirmation of reports that Israel had launched air strikes on a convoy in Sudan said to be carrying weapons for Gaza.