Johor Menteri Besar Khaled Nordin must explain the claims of logging, allegedly involving the royalty, being carried out in the state, Amanah deputy president Salahuddin Ayub said.
He made the call after Pelindung Khazanah Alam Sekitar Malaysia (Peka) president Shariffa Sabrina Syed Akil was arrested last week for insulting the Johor sultan by posting on Facebook about logging on land belonging to the monarch.
Like all Malaysians, Salahuddin said, he upholds the position of constitutional monarchy.
Defending the constitution, he said, is the obligation of citizens and rulers.
The constitution, he added, protects the rakyat's freedom to fight for causes, such as land rights and protection of the environment.
"The country proclaims that 'no one is above the law', so I too fight to defend this principle," Salahuddin said in a statement.
"A constitutional monarch does not breach the constitution and rule of law, which guarantees fairness for all citizens.
"A constitutional monarch upheld by the people defends the people and nation," he added.
Shariffa Sabrina, who holds the title "Puan Sri", and her assistant were remanded for three days for the Facebook posting.
According to the police, they were being investigated under Section 233(1)(a) of the Communications and Multimedia Act 1998, which relates to "improper use of network facilities or network services".
Her group, Peka, consistently speaks out against logging activities.- Mkini