Washington, United States | Former US president Bill Clinton and British premier Tony Blair's political friendship was matched by an easy-going personal relationship that helped them through some tough crises.

A collection of transcribed phone conversations from 1997 to 2000 just released by Clinton's presidential library reveals them working closely on the problems of the global economy, Northern Ireland's peace process and the war in Kosovo. 

But it also captures moments of humor -- including running gags about bananas and Scottish knitwear -- and offers of comfort, as when the US leader calls Blair after the Omagh bombing or the death of Princess Diana.

On September 1, 1997 -- one day after Diana died as a result of injuries sustained in a Paris car crash -- Clinton picked up the phone: "Tony?"

"Hi Bill," the prime minister replied. "It's a grim business, a very grim business." 

Clinton continued: "It's awful, it's really awful, We're up here on Martha's Vineyard vacationing and we're with a lot of people who knew her."

"We saw her just weeks ago when we hosted her for lunch with Prince William, he's a great kid," Blair replied. Clinton agreed: "Yeah, I worry a lot about those kids now."

More than 500 pages of transcripts were released, but much of it is redacted, particularly Blair's side of the dialogue, as US authorities would not normally declassify material provided in confidence by a foreign leader.

So comfortable were the two leaders in their relationship, their jokes could verge on the risque.

When Blair wondered whether it would be appropriate for him, while waiting for Clinton to return late to Washington, to sleep in a White House bed once used by Winston Churchill, the president replied: "As long as you don't parade around naked before the bath. You're too young and too trim." 

The release of the transcripts triggered a flurry of amusement online, with many on social media wondering about repeated jokes between the men of the subject of bananas and cashmere sweaters from Scotland.

- A big, ugly banana -Both leaders apparently found the topic of bananas amusing and Clinton especially loved to return to it.

In February 1999, when US vice president Al Gore attended a meeting in London with Blair's deputy prime minister John Prescott, he was amused to find the only decoration was a bowl of bananas.

"I heard all about it. He was very happy," Clinton told Blair. "My staff won't let me talk to you unless I have a banana at hand. I'm sitting here with a banana. It's a big, ugly brownish one."

Blair's reply: "Now Bill, I thought we should have a word about Kosovo."

Blair and Clinton also joked about the president's fondness for wearing Scottish cashmere jumpers when golfing, a passion so strong that it risked offending another Celtic constituency.

Discussing a foreign dignitary involved in negotiations over Kosovo, Clinton said: "I thought I could have my whole wardrobe of Scottish cashmere brought down to him. The Irish wouldn't like it. Hell, I think even the Irish sweaters I have are Scottish."

In a later exchange, after Blair promises to send more cashmere from Scotland, Clinton even jokes about taking British nationality and crossing the Atlantic to indulge his Highland passions.

"The daily papers today are filled with China being pissed off and Russia threatening war," he said, complaining of the daily grind of White House life.

"What I want is that when I am done here to be made an honorary UK citizen and give me a seat from Scotland next door to a good golf course."