The Vatican on Wednesday urged "greater reserve" ahead of the conclave to elect a new pope, as US cardinals scrapped their daily press briefings saying that "concern was expressed about leaks".

US cardinal Timothy Dolan, the archbishop of New York, and Francis George, the archbishop of Chicago, had been due to address journalists at the Pontifical North American College in Rome.

"Concern was expressed about leaks of confidential proceedings reported in Italian newspapers," the US Conference of Catholic Bishops said.

"As a precaution, the cardinals have agreed not to do interviews," it added in a statement.

Italian media earlier on Wednesday reported there were "sparks" flying at pre-conclave meetings between US and German cardinals on one side and Italian ones on the other.

The reports said US and German prelates were keen to have longer discussions ahead of the conclave, while the Italians wanted to move to a papal election as quickly as possible.

Vatican spokesman Federico Lombardi said he was not surprised by the decision, saying there was a general feeling of the need for "greater reserve" as the conclave looms and stressing that other countries did not have a similar media presence.

All cardinals taking part in the meetings have to swear an oath of secrecy on pain of excommunication not to discuss the papal election but US cardinals in previous briefings had spoken in more general terms about their priorities.

US cardinals had also emphasised the need for a reform of the Roman Curia, the government of the Catholic Church which has been heavily criticised in recent years for intrigue and inefficacy.

"It seems natural that the path towards the conclave leads progressively to greater reflection and discretion," Lombardi said.

"The tradition of the conclave and the path towards it is one of discretion," he said.