Obama hails 'essential relationship' on UK visit

AFP - US President Barack Obama basked Tuesday in the royal pageantry of a state visit to Britain, given an extra dash of glamour by a brief encounter with Prince William and his new bride Catherine.

The president and his wife Michelle were welcomed by Queen Elizabeth II and a 41-gun salute in the gardens of Buckingham Palace at the start of a two-day visit mixing pomp with serious diplomacy.

Obama's time in London will include talks with Prime Minister David Cameron aimed in part at spurring a push for democracy in the wake of the Arab Spring.

But the focus of Tuesday was a day with the royals, starting with a meeting with William and Catherine, now known as the Duke and Duchess of Cambridge, less than a month after watching their fairytale wedding on television.

In a picture released afterwards, Catherine, wearing a pale coffee-coloured dress and looking tanned after her honeymoon in the Seychelles, chatted with the First Lady while the prince talked with Obama.

The Obamas were not invited to the April 29 wedding so it was the first opportunity for them to congratulate the royal couple.

Later, the queen was to fete Obama with all the trappings of a state dinner before the Obamas retire to the palace's sumptuous Belgian suite, last used by William and the former Kate Middleton on their wedding night.

But the 24-hour demands that follow a US president everywhere shadowed the London pomp, as Obama took time out to say he was "heartbroken" at the toll of vicious tornados which ripped across the US midwest, killing 116 people.

The serious political business of the visit happens on Wednesday, and Obama and Cameron limbered up for their talks with a vow to support those risking their lives for reform in the Arab world.

"We will not stand by as their aspirations get crushed in a hail of bombs, bullets and mortar fire. We are reluctant to use force, but when our interests and values come together, we know we have a responsibility to act," they wrote.

"We will stand with those who want to bring light into dark, support those who seek freedom in place of repression, aid those laying the building blocks of democracy," they said in an article in the Times newspaper.

In a riff on the so-called "special relationship" between the US and Britain, Obama and Cameron also heralded a new "essential relationship" between the countries.

Diplomatic and military maneuvering is heating up over Libya ahead of the G8 summit in France, Obama's next stop on a four-nation European tour which began with a journey to his ancestral roots in Ireland and also takes in Poland.

Mindful that no US leader can afford to hobnob with royals abroad while a disaster unfolds at home, Obama said he would visit the Missouri tornado disaster zone on Sunday, hours after returning from Europe.

On Tuesday, after the formal welcome and lunch, the queen showed the Obamas US-related items from the royal family's archives.

In the traditional exchange of gifts, the royals gave the Obamas a gift of letters to and from US presidents to Queen Victoria in the 19th century.

In return, the president gave the queen and her husband a leather-bound album of memorabilia of a visit made by her parents, King George VI and Queen Elizabeth, to the US in 1939, and equestrian-related items reflecting the royals' love of horses.

The queen struck up a visibly close friendship with Michelle Obama when the Obamas visited Britain for the first time in 2009, with both women putting their arms around each other in a highly unusual gesture.

"There is a genuine, genuine -- and I really mean this -- a genuine warmth between the two families," a palace spokesman said.

The Obamas also laid a wreath at the tomb of the Unknown Warrior in Westminster Abbey.

In a slice of history, America's first black president passed beneath a statue of civil rights leader Martin Luther King, installed above the ancient abbey's Great West Door in 1998.

On Wednesday, the president is granted the rare honour of addressing both houses of the British parliament.