Pope Francis on Thursday urged Catholic cardinals to back his plans to reform the scandal-hit Vatican bureaucracy in order to help the Church reach out to believers more effectively, including on issues such as the environment.

The message came at the start of a two-day meeting of senior clerics from all corners of the globe which will review plans for the creation of two new super-ministries, one of which will include environmental issues among its responsibilities.

One ministry will focus on laity, family and life issues, the other on charity and peace, which will include the green issues on which Francis has indicated he wants the Church to take a lead.

The elevation of the environment to such a prominent position in the Church's priorities is particularly significant in light of Francis's view that climate change is mostly man-made.

The Church is expected to take a stance in the global warming debate when Francis issues an eagerly-awaited encyclical on the environment at some point this year.

Reform of the curia, the Vatican bureaucracy, is also on the pope's agenda following a string of revelations about internal bickering, cronyism and corruption under his predecessor Benedict XVI.

In December, Francis suggested the Vatican's administrative hierarchy was beset by a "spiritual Alzheimer's," that was reflected in a culture of unbridled ambition and gossipy navel-gazing amongst senior officials.

Vatican spokesman Federico Lombardi said the goal of reform was to ensure better and more efficient collaboration between departments of the Vatican.

Lombardi said the shake-up was proof the Church was taking environmental issues seriously.

Of the 227 cardinals around the world, 165 were in Rome Thursday with several more due to arrive during the talks.

The pope will welcome 20 new cardinals to the ranks on Saturday, including 15 who are below 80 and would therefore be entitled to vote in a conclave to decide a new pontiff in the event of something happening to the current one.