Mexican Catholic priests are among the most persecuted in the world, with attacks having increased by 80 per cent over the past two years, a new report has found.

Released by the Mexican Catholic Multimedia Centre (CCM), the report confirms that six priests have been murdered and three others the victim of forced disappearances since President Enrique Pena Nieto was elected in July 2012.

The Mexican government has been accused of being "unwilling" to protect the religious freedom of its people. CCM is urging authorities to "provide security in areas with a significant presence of organised crime."

Priests are often targeted as a result of denouncing criminal groups, or because they are working to help people exploited by violent gangs, such as victims of human trafficking or drug addicts. Churches are also seen as an attractive target for extortion and front for money laundering.

The report comes in the wake of Father José Ascensión Acuña's murder last month. His body was found in the Balsas River near Santa Cruz de Las Tinajas after he disappeared on September 21.

Over 80 per cent of the Mexican population are Catholic. President Nieto met with Pope Francis at his inaugural Mass, and later travelled to the Vatican for an official meeting with the Pontiff last July. The Mexican constitution also guarantees freedom of religion or belief to all its citizens.

However, the Vatican has denounced Mexico as the country with the highest number of attacks on Catholic religious leaders in the world. A Christian Solidarity Worldwide (CSW) investigation into religious liberty in the state of Chiapas also found that Protestant leaders are facing similar treatment.

The inquiry found that violations of religious freedom are on the rise in Mexico. Forced conversions, physical violence and the deprivation of water were among the violations reported.

"At best, the state and municipal governments are unable or unwilling to protect the religious freedom of their citizens and to address these human rights violations. At worst, they are passively or actively complicit in the violations of religious freedom," the CSW report concluded.

Chief Executive of CSW, Mervyn Thomas has branded the latest findings "shocking".

"The continued increase in the number of attacks on religious leaders in Mexico, making it one of the most dangerous places in the world for church leaders, is shocking and deeply concerning," he said.

"We urge the Mexican government to implement effective strategies to provide security to civilian populations in areas with a strong influence of criminal groups, and to develop strategies to support civil society actors like churches and religious leaders as they come under threat."

Thomas continued: "CSW also calls for a full investigation into the forced disappearance and subsequent murder of Father Ascensión Acuña and the prosecution of those responsible.

"We urge the international community to engage with the Mexican government on these matters and to recognise the role that many religious leaders play, not only as leaders of their churches, but also as voices for peace, justice and integrity as human rights defenders."