Pope Francis set up a special commission of experts to review annulments last year
Pope Francis and Angela Merkel are among the favourites to receive the Nobel Peace Prize when it is announced in Norway on Friday morning.
The Pope’s opposition to nuclear weapons and role in a deal between the US and Cuba boosted his chances, said Norwegian state broadcaster NRK.
Angela Merkel, the German chancellor, has been tipped for her stance on the refugee crisis unfolding in Europe.
But the prize committee’s decision is notoriously hard to predict.
In depth: History of the Nobel Peace Prize
Other contenders for the award include:
Mussie Zerai, an Eritrean priest who founded a humanitarian organisation for refugees
Denis Mukwege, a gynaecologist from the Democratic Republic of Congo who has treated thousands of gang rape victims
Clive Stafford-Smith, the veteran human rights campaigner and lawyer.
Among the more high profile nominees for the £700,000 ($1.1m; €950,000) prize are:
Edward Snowden, the former NSA contractor who leaked details of US surveillance programmes to the press
John Kerry and Javad Zarif, the US and Iranian foreign ministers who brokered a historic nuclear deal
The charity Medecins Sans Frontieres, for its work on the West African Ebola outbreak.
Around 273 individuals and organisations have been nominated for the prize by past winners, political leaders and other dignitaries.
Last year’s award was won by Malala Yousafzai, the Pakistani education activist and Kailash Satyarth, an Indian child rights campaigner.
Previous Nobel peace prize laureates include anti-apartheid hero Nelson Mandela, US President Barack Obama, the Dalai Lama and Burmese opposition leader Aung San Suu Kyi.
In 2012 the prize was awarded to the European Union in recognition of its contribution to peace and reconciliation, democracy and human rights in Europe.