Rafizi Ramli, vice-president of the People's Justice Party (PKR), was arrested outside the Malaysian parliament on Tuesday.
Gunnlaugsson says he does not want to obstruct any further reform of the financial system by continuing as the prime minister.
Najib, who is trying to shake off numerous financial scandals, said Mahathir betrayed the Malays by joining ranks with the opposition.
Mahathir reiterates his stance that he had asked Najib not to go ahead with GST.
Minister says long-standing political crisis has caused an erosion in investor confidence and hurt the economy..
Quang, 59, is a former police general from the ministry of public security.
The newly created advisory position allows the 70-year-old leader a larger role across the government.
Rodrigo Duterte and Jejomar Binay are statistically tied for second place with 24 percent and 23 percent voter preference.
'As much as $15 million was spent on clothes, jewelry and cars in countries including the US, Malaysia and Italy'
Htin Kyaw takes over from semi-civilian ruler Thein Sein to become the first elected civilian leader in more than 50 years.
Myanmar is undergoing a landmark transition from rule under military junta to elected democracy.
Ruling United Malay National Organisation says it plans action against dissenters Muhyiddin Yassin and Mukhriz Mahathir.
Earlier this week, Mahathir filed a lawsuit accusing Najib of corruption and abuse of power.
Stepping out of the sombre state dinner mood, Obama took tango steps with pro dancer dancer Mora Godoy.
Mahathir says Najib misused his power by trying to smother investigations into both these scandals.