The Prince of Wales will urge nations to confront intolerance and bigotry head-on and make striving for a “better tomorrow” their “common cause” during a ceremony marking Germany’s National Day of Mourning.

In a speech at the Bundestag on Sunday, Charles is also expected to call on Britain and Germany to “reaffirm” their bond as the two nations “begin this new chapter in our long history”.

The heir to the throne’s comments will come as the UK’s talks on a post-Brexit trade deal with the EU look set to go to the wire.

The prince will also say that the global crises of the coronavirus pandemic and climate change “demand” that Britain and Germany “act together”.

Charles and his wife the Duchess of Cornwall will become the first members of the royal family to attend Germany’s remembrance ceremony in Berlin on Sunday – the couple’s first joint official overseas visit since the start of the pandemic.

The prince is expected to say in his speech: “We must be resolute in addressing acts of unspeakable cruelty against people for reasons of their religion, their race or their beliefs, wherever they occur in the world. We must stand alongside each other in determined defence of the future we owe our children and our grandchildren.

“The challenges to that future are manifest – whether from this dreadful pandemic which threatens not just our public health but our prosperity and security; or from the existential threat to our planet, and our way of life, from climate change and catastrophic biodiversity loss.

“These crises demand that we act together, and the partnership between the United Kingdom and Germany offers such a vital opportunity in this regard. We are heavily invested in each other’s futures, such that our national interests, whilst distinct, will always be entwined.

“As our countries begin this new chapter in our long history, let us reaffirm our bond for the years ahead.

“Let us reflect on all that we have been through together, and all that we have learned. Let us remember all victims of war, tyranny and persecution; those who laid down their lives for the freedoms we cherish, and those who struggle for these freedoms to this day. They inspire us to strive for a better tomorrow – let us make this our common cause.”

The royal family has carried out a string of European visits since the 2016 referendum result decided the UK would leave the EU, and this latest trip is likely to be viewed as part of the monarchy’s “soft diplomacy” to renew and strengthen friendships with countries on the continent.

When Charles’ son the Duke of Cambridge visited Germany in 2016, William said that the depth of Britain’s friendship with Germany will not change after Brexit.

Ahead of his trip, the prince held a telephone meeting with Germany’s Chancellor Angela Merkel on Thursday.

The official Twitter account for Charles and Camilla shared a picture of the prince to mark his 72nd birthday, which he celebrated on Saturday.

In the autumnal snap, the heir to the throne is wearing a kilt and smiling towards the camera as he stands next to a tree.

Clarence House announced the brief visit to Germany earlier in the week and said in a statement the couple had been invited by the president of Germany, Frank-Walter Steinmeier.

The statement added: “Their Royal Highnesses will also attend the wreath-laying ceremony at the Neue Wache Memorial, before joining the Central Remembrance Ceremony at the German parliament, where the Prince of Wales will deliver a speech.

“The National Day of Mourning will this year focus on the German-British friendship, which has grown in the 75 years since the end of the Second World War.

“The event pays tribute to the Allied commitment to the liberation from Nazi occupation and to the reconstruction, re-democratisation and subsequent reunification of Germany. It remembers all victims of war and tyranny.”