One of former prime minister Najib Abdul Razak's former special aides has been remanded in the investigation of the company awarded the solar hybrid project for rural schools in Sarawak.

The 44-year-old was reportedly arrested on Monday, when he was called to the Malaysian Anti-Corruption Commission (MACC) office.

The next day, magistrate Shah Wira Abdul Halim granted a four-day remand to investigators, The Star reported today.

"We were made to understand that he had asked for a huge sum (from the company which was awarded the project)," an MACC source familiar with the matter said.

The amount the man asked for is believed to be in the millions of ringgit, though the source did not reveal the exact figure.

The money also was reportedly not transferred.

"Nonetheless, we need to question him as there are allegations that he solicited for money," the source said.

It was reported that MACC investigations director Simi Abd Ghani confirmed the man was remanded but did not elaborate further.

Malaysiakini revealed in June that the Education Ministry under the previous administration had awarded the solar hybrid project for 369 rural schools in Sarawak to a Bintulu-based company under "direct orders" from Najib.

Documents sighted also showed that the contract tender bypassed the Education Ministry's standard operating procedures and procurement processes.

Aside from this man, three other individuals have also been detained by the MACC to facilitate investigations into the case.

However, the Bintulu-based company awarded the project has denied any wrongdoing.