Pope Francis has called on world leaders to protect the safety of migrants following a sharp increase in drownings across the Mediterranean.

“There have been dramatic reports of shipwrecks of boats laden with migrants in the waters of the Mediterranean,” Francis told a crowd of thousands gathered in St Peter’s Square. “I express my sorrow in the face of these tragedies and assure my prayers for those missing and their families.”

The Pope said he was making “a heartfelt appeal for the international community to act decisively and promptly” so that the drownings would stop and “to guarantee security, [and] respect for the rights and dignity of all.”

On Wednesday 30 people died when a boat carrying 150 migrants sank close to the coast of northern Cyprus with charities reporting that the numbers of deaths in the Mediterranean reaching 600 in the period from the middle of June to the middle of July.

French aid organisation Medicin Sans Frontiers says the increase in drownings has been fuelled by the decision of the new Italian government to prevent migrant rescue boats from docking in the country’s ports.

For Francis, the care of migrants has been a core concern of his papacy and after hearing news of migrant drownings of the coast of southern Italy in 2013 he chose the island of Lampedusa, a major arrival point for refugees from North Africa, as the place of his first papal visit outside of Rome.

But his defence of refugees stands in contrast to Matteo Salvini, Italy’s Deputy Prime Minister and Minister of the Interior, who has taken a tough anti-migrant line and who polls show is growing in popularity.

The Pope’s appeal for migrants came after eh told the crowd that an “unexpected emergency” mean that plans must be changed in order to respond to the needs of others.

Christians, he explained, are sometimes unable to complete their projects and need to show “flexibility and availability”.

The Pope was reflecting on the Gospel of Mark 6:30-34 where Jesus encourages the apostles to rest following an intense period of work and teaching. A large crowd, however, continues to follow them so Jesus, after seeing them and having “compassion for them”, starts teaching.

This, Francis stressed, offers an insight into the “intensity” of Christ’s mission and give us the three “verbs” of a Shepherd which he described as: “to see, to have compassion [and] to teach.”

“The gaze of Jesus is not a neutral one or, worse, cold and detached look,” the Pope said. “Jesus always looks with the eyes of the heart, and his heart is so tender and full of compassion, that he knows how to grasp the hidden needs of people. His compassion does not simply indicate an emotional reaction to a situation of unease of the people, but it is a lot of more: it is the attitude of God towards man and his history.”

While some in the crowd expected Jesus to perform a miracle, Francis explained, it was significant that he chose to “teach” them instead.

“We all need the word of truth, to guide us and enlighten the path,” the Pope said. “Without the truth, which is Christ himself, it is not possible to find the right orientation of life. When one moves away from Jesus and his love, one loses oneself and existence turns into disappointment and dissatisfaction.”

He added: “with Jesus on the side we can proceed with security, we can overcome the trials, we progress in love for God and for our neighbour. Jesus has made himself a gift for others, thus becoming a model of love and service for each one of us.”