Former Prime Minister Tun Dr Mahathir Mohamad should apologise to Prime Minister Datuk Seri Najib Tun Razak and Malaysians for his allegations over the RM2.6 billion donation.

Communications and Multimedia Minister Datuk Seri Salleh Said Keruak said Najib had been consistent with his response on the issue, even though various baseless accusations were leveled against him.

"From the very beginning the prime minister had said that the funds were donated by the Saudi government and he was very consistent (with his response)," he told reporters after a 'Mesra Siswa Perdana 2016' programme at Sekolah Menengah Kebangsaan Kadok here, today.

Also present at the launch of the five-day programme was Ketereh MP Tan Sri Annuar Musa and 800 undergraduates from 18 public universities.

Saudi Arabian foreign minister Adel Al-Jubeir yesterday confirmed that the the donation to Najib was from his country and "nothing was expected in return."

Salleh said the admission concurred with investigations conducted by the Malaysian Anti-Corruption Commission (MACC) and Attorney-General Tan Sri Mohamed Apandi Ali that there were no elements of corruption and the money was not from 1Malaysia Development Berhad (1MDB).

"Now that the truth is out, Tun Mahathir should apologise to the prime minister and Malaysians for what he had done which had caused certain parties to have a negative view of the country.

"By right we should give our undivided support to the government in addressing current issues, especially in economic issues, that is most crucial," he said.

On the open debate between Urban Wellbeing, Housing and Local Government Minister Datuk Abdul Rahman Dahlan and Penang Chief Minister Lim Guan Eng on the Taman Manggis land issue, he said both parties should take heed of the advice given by Inspector-General of Police Tan Sri Khalid Abu Bakar and MACC director Datuk Azam Baki.

"Based on information (I received) the IGP had advised against the debate as it will jeopardise investigations," he said.

On April 6 Abdul Rahman had challenged Lim to an open debate over the issue and the DAP secretary-general accepted it.