"We're not against the freedom of belief, but we do fear the consequences of this provision for our Islamic identity," the general secretary of the Justice and Development Party [PJD], Abdelilah Benkirane, told AFP.
Several sources last Thursday told AFP that the future constitution stipulates that "Islam remains the religion of the state, but the freedom of belief is guaranteed under the law" where it does not disrupt public order.
"What does 'freedom of belief' mean? That secular people will be allowed to publicly break the fast during Ramadan [the Muslim holy fasting month]? That sexual freedom and homosexuality become banal and public practices?" Benkirane asked.
The PJD is in opposition in the lower house of parliament, with 46 of the 325 seats.
"We're not against the freedom of belief, but Morocco is a Muslim country with its laws. In France, they are banning the full-faced veil in the name of the law. We're completely capable of voting against this new constitution," he added.
Abdeltif Menouni, the president of the consultative commission on reforming the constitution, which was set up in March, on Friday gave King Mohammed VI a draft plan for a new constitution, which will go to a referendum in July.
According to a member of the commission, the future constitution will reduce the prerogatives of the king of the north African country and give more power to the government.
On March 09, Mohammed VI announced major constitutional reforms, providing notably for the principle of the separation of powers and for strengthening the powers of the government chief.