Israel further tightened its grip on the West Bank Wednesday, arresting another 65 people, as Palestinian president Mahmud Abbas lashed out at those behind the kidnapping of three Israeli teenagers.

As the hunt for the youths entered its sixth day, there was no let-up in Israel's drive to deal a crushing blow to the West Bank infrastructure of Islamist movement Hamas, which it has blamed for the kidnapping.

As troops pressed their biggest arrest operation in years, imposing a tight lockdown on huge swathes of the West Bank, Abbas blasted those behind the teens' disappearance, saying they were trying to "destroy" the Palestinian people.

And he defended the security coordination between the Palestinian and Israel, sparking a furious denunciation by the Hamas.

"Those who kidnapped the three teenagers want to destroy us. We will hold them accountable," Abbas told a meeting of the Organisation of Islamic Cooperation in Saudi Arabia.

"It is in our interest to have security coordination with Israel, because that would help protect us," he said.

"We will never have another intifada (Palestinian uprising) -- that would destroy us."

Hamas denounced his remarks as "harmful" to a fledgling reconciliation deal between it and the Palestinian leadership, which saw an interim government of technocrats replace rival administrations in the West Bank and Gaza earlier this month.

The exchange was the first public sign of a major dispute between the sides since the unity deal was signed in April, ending years of bitter and sometimes bloody rivalry.

Pundits have said Israel is seeking to use the massive military operation to bring about the collapse of the newly formed unity government, established with the backing of its foe Hamas.

- 'Unjustified, harmful' -

"President Abbas's statements on security coordination with Israel are unjustified, harmful to Palestinian reconciliation," Hamas spokesman Sami Abu Zuhri said.

The Palestinian leader's remarks in Jeddah were also "a psychological blow to the thousands of Palestinian prisoners suffering a slow death in the occupation's jails," he said, referring to around 5,000 detainees being held by Israel.

Although Israeli Prime Minister Benjamin Netanyahu has directly accused Hamas militants of being behind the kidnapping, the movement has dismissed his claims as "stupid".

Palestinian militants have long backed a policy of kidnapping Israelis for use as bargaining chips to secure the release of prisoners.

In October 2011, Israel began the staged release of 1,027 Palestinian prisoners in exchange for Gilad Shalit, an Israeli soldier held in Gaza by Hamas militants for more than five years.

So far, there has been no claim of responsibility for the teens' disappearance.

- Ramadan disruptions likely -

Overnight, Israeli troops arrested another 65 Palestinians, among them 51 who had been released as part of the Shalit deal, in a move hailed by Netanyahu as sending "an important message."

Defence Minister Moshe Yaalon said the re-arrests were a "clear message that not only are we taking action to release the boys, but also that when there is an abduction, we will put those who have been released back in jail."

Since the searches began early Friday, troops have arrested 240 Palestinians, searched more than 800 locations and raided 10 Hamas-run institutions, the army said.

But despite days of intensive military operations, there appeared to be no end in sight, with troops focusing on the southern city of Hebron and the surrounding area.

"They kicked the door in at 7:30 am (0430 GMT) and told us to get out... If our relatives didn't live nearby, we'd have ended up on the street," said Umm Amr, a mother of four who lives in Taffuh village.

Meanwhile, the International Committee of the Red Cross said it was "intensifying its efforts" to provide aid to Palestinians during the operation.

But the Red Cross warned the operation was "fuelling frustration and may trigger further violence."

Officials warned the operation could run into the Muslim holy month of Ramadan, which begins at the end of June.

Others said the normal easing of security measures during the fasting month could be suspended.