Security, migration and the war in Gaza were some of the issues raised as world leaders congratulated their “friend” Sir Keir Starmer on his General Election victory.

Canadian Prime Minister Justin Trudeau was among the first to share a message as he said he hopes to build a “progressive, fair future” with the Labour leader – who he described as “my friend”.

“Congratulations, (Sir Keir), on a historic U.K. election victory,” Mr Trudeau posted to X.

“Lots of work ahead to build a more progressive, fair future for people on both sides of the Atlantic. Let’s get to it, my friend.”

A key issue Sir Keir will face in the early days of his premiership will be the war in Gaza, and Israeli president Isaac Herzog said he looked forward to working together to bringing home hostages taken by Hamas.

“I send my warmest congratulations to (Sir Keir),” Mr Herzog posted to X.

“As he prepares to enter Downing Street as Prime Minister, I look forward to working together with him and his new government to bring our hostages home, to build a better future for the region, and to deepen the close friendship between Israel and the United Kingdom.”

Mr Herzog also expressed his “deepest appreciation and gratitude” to outgoing Prime Minister Rishi Sunak “for his leadership and for standing with the Israeli people especially during this most difficult period”.

Eight years since the Brexit vote, European Council president Charles Michel declared Sir Keir’s election would mark a “new cycle” for the UK as he looked forward to working together on “common challenges”.

“Congratulations @Keir_Starmer on a historic election victory in the UK,” Mr Michel posted to X.

“(The European Union and UK) are crucial partners, cooperating in all areas of mutual interest for our citizens.

“I look forward to working with you and your government in this new cycle for the UK.

“See you soon in the European Political Community meeting on 18 July in the UK where we will discuss common challenges, including stability, security, energy and migration.”

Sir Keir will also be scrutinised over his approach to Russia after its invasion of Ukraine, and Kaja Kallas, the prime minister of Russian neighbour Estonia, shared a message highlighting “common security”.

“Congratulations on your historic election victory, (Sir Keir),” Ms Kallas posted to X.

“Estonia and the UK are the strongest of allies and the closest of friends. The UK’s commitment to our common security is valued by every Estonian.

“I’m sure our excellent cooperation will only continue to thrive.”

Australian prime minister Anthony Albanese said he is looking forward to working constructively with Sir Keir, describing him as his “friend”.