It is more than 37 years since a pope visited the mineral-rich but conflict-ridden country.

More than one million people in the Democratic Republic of Congo attended Pope Francis' Mass in the capital of Kinshasa on Wednesday, the Vatican Press Office said.

Francis' trip to Congo, the first papal visit made since 1985, attracted a public holiday to enable as many people as possible to attend.

The visit, which comes at a time the African nation is plagued by armed fighting and a worsening refugee crisis, is part of a six-day trip in DRC and South Sudan -- two countries where Catholics make up about half of the population. Both countries have abundant natural resources, but are grappling with poverty and strife.

Francis was greeted by jubilant crowds singing and dancing at N'Dolo Airport from the early hours of the morning.

Speaking to attendees in his homily about peace, Francis challenged those who wield weapons, saying: "May it be the right time for you who in this country call yourself a Christian but commit violence. To you the Lord says, 'Put down your arms and embrace mercy.'"

"We Christians are called to cooperate with everyone, to break the cycle of violence, to dismantle the machinations of hatred," he added, as he urged warring sides to forgive one another and grant their opponents a "great amnesty of the heart".

He went on to espouse the benefits of cleansing one's heart of "anger and remorse, of every trace of resentment and hostility".

Francis noted that Congo was suffering from "wounds that ache, continually infected by hatred and violence, while the medicine of justice and the balm of hope never seem to arrive," Reuters reported.

Decades of militia violence have gripped the country as government troops struggle to curb M23 rebel group, which seeks control of the nation from its stronghold in eastern DRC, leaving many dead and displacing thousands.

According to the United Nations, some six million people have been forced to flee their homes in DRC. The UN World Food Programme also reports that 26 million people in the country face severe hunger.

Francis, whose second day of visit coincides with a continuation of fighting between the Congolese army and rebels, met with victims of violence from the east during his visit and said he was "left without words" after hearing their harrowing stories. 

"We can only weep in silence," he said as he thanked the victims for their courageous testimony.

The Pope met President Félix Tshisekedi Tuesday and delivered a speech condemning historical exploitation of Africa's resources, which he described as "economic colonialism".

He also addressed Congo's plight, as minerals have played a key role in more than three decades of armed conflict there, saying: "Hands off the Democratic Republic of the Congo! Hands off Africa! Stop choking Africa, it is not a mine to be stripped or a terrain to be plundered."

Francis, whose planned visit to the eastern city of Goma has been cancelled for security reasons, is scheduled to leave Kinshasa Friday for South Sudan's capital of Juba, where he will be joined by Archbishop of Canterbury Justin Welby and the Moderator of the General Assembly of the Church of Scotland, Iain Greenshields.