Pope Francis told members of the Vatican bureaucracy today that reforms to make it more efficient and honest will move ahead "with firm resolve", despite scandals that have rocked the Church.

At the start of traditional Christmas greetings to the Curia, as the central Vatican administration is known, the pope said he was suffering from a flu and excused himself for reading the speech sitting down.

However, he did not show any outward signs of illness and read his speech in a strong voice, noting cases "of resistance difficulties and failures" by some individuals in the central administration who were opposed to his reform drive.

"It seems necessary to state what has been, and ever shall be, the object of sincere reflection and decisive provisions. The reform will move forward with determination, clarity and firm resolve ..." he said.