Malaysian authorities have arrested four suspected militants and confiscated a weapon along with Islamic State group (IS) documents, national police chief Khalid Abu Bakar said Saturday.

Security forces have been on high alert in the predominantly-Muslim country in the wake of deadly coordinated attacks in neighboring Indonesia earlier this week that were claimed by IS. Seven people, including five assailants, were killed during the incident.

Malaysian Prime Minister Najib Razak on Thursday defiantly rejected calls to step down over a political funding scandal as the ruling party doubled down on its support for him in the face of an uncertain electoral outlook.

Najib vowed not to give in to unnamed "traitors" seeking his removal, as he addressed the annual assembly of the ruling United Malays National Organization (UMNO), the most closely watched in years due to the current tumult.

Critics have hit out against a new Malaysian security law granting unprecedented emergency powers to the government, which they say is aimed at quashing challenges to scandal-tainted Premier Najib Razak and is propelling the country toward dictatorship.

Malaysia's parliament passed the National Security Council Bill late Thursday -- the final day of the chamber's 2015 sitting -- just two days after it was tabled, spurring opposition accusations that it was quickly rammed through to thwart scrutiny and debate.

Influential former Malaysian premier Mahathir Mohamad and some key ruling party members demanded Monday that embattled Prime Minister Najib Razak answer a barrage of corruption allegations.

On the same day, a whistle-blower and his lawyer detained for their efforts to expose graft allegations against Najib were charged with attempting to "sabotage" the country's banking sector.

Malaysian authorities have arrested three people including a Syrian and an Indonesian national on suspicion of planning terror attacks against domestic and foreign targets, police and news reports said Friday. 

The announcement came a day after the U.S. and Australian embassies had warned their citizens to avoid a popular Kuala Lumpur tourist area on Thursday due to an unspecified security threat.

Malaysian authorities on Friday stepped up a search for survivors from a boat that sank while crammed with Indonesian migrants as the death toll rose to 15, the Malaysian coastguard said.

The count of victims increased from 14 with the recovery of another body from the Malacca Strait, while four more passengers were rescued, said Mohamad Aliyas Hamdan, a Malaysian Maritime Enforcement Agency official.

French prosecutors confirmed Thursday that a wing part found on a remote Indian Ocean island was from ill-fated Malaysia Airlines flight MH370, a month after tests on the flaperon began.

"It is possible today to say with certainty that the flaperon discovered on Reunion island on July 29 came from flight MH370," Paris prosecutors said in a statement, confirming claims made by Malaysia's prime minister last month.

At least 13 people have drowned after a small wooden boat, believed to have been carrying about 70 Indonesian migrants, sank in the Malacca Strait early Thursday, Malaysian officials said. 

The vessel went down in choppy waters off Malaysia's western coast near the coastal town of Sabak Bernam in central Selangor state, Mohamad Aliyas Hamdan, the local head of the Malaysian Maritime Enforcement Agency, told Agence France Presse.

Organizers of a huge weekend demonstration demanding the Malaysian prime minister's removal over graft allegations said Tuesday they had been summoned by police, as Transparency International spoke of a "corruption crisis" in the country.

Several protest leaders were ordered to report to police and give statements on Wednesday, said Maria Chin Abdullah, chair of Bersih, the coalition of Malaysian NGOs and activist groups that staged the two days of rallies.

Malaysia's government reclaimed the streets of the capital Monday after massive weekend protests demanding the premier's ouster, staging its own show of force with National Day celebrations attended by thousands.

With Prime Minister Najib Razak presiding, masses of flag-waving spectators cheered a colorful parade of soldiers, police and civil servants through the city center, symbolically underlining the government's clout despite pressure for change.