Britain's Prime Minister David Cameron and King Abdullah II of Jordan held talks Saturday on ending the "appalling daily slaughter" in Syria, Cameron's Downing Street office said.
They also discussed the Middle East peace process and Britain's marathon efforts to deport radical cleric Abu Qatada back to Jordan.
Cameron welcomed King Abdullah with a handshake on the steps of his 10 Downing Street office before they sat down for talks on the terrace in the back garden.
The two then went to watch Trooping the Colour, Queen Elizabeth II's official birthday celebrations, which took place over the garden wall in Horse Guards Parade.
"The prime minister met King Abdullah of Jordan at Downing Street," said a statement from the premier's office.
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The plan hammered out by Kofi Annan, the UN-Arab League envoy to Syria, aims to put in place a ceasefire and end the violence on both sides, as well as start a Syrian-led political process to meet the aspirations of the Syrian people.
The statement also said that Cameron and Abdullah "agreed on the importance of progress towards a two state settlement between Israel and the Palestinians through direct negotiations.
"The prime minister welcomed King Abdullah's vision for political and economic reform and the progress made so far.
"They also agreed on the need to return Abu Qatada to Jordan and that both governments would continue to work together on this issue.
"After the meeting, the king joined the prime minister at the Trooping the Colour ceremony."
Meanwile a female protest took place outside the Syrian embassy in London against President Bashar al-Assad's crackdown on demonstrations.
Women in headscarves chanted slogans and waved placards reading "Stop killing people" and "Like father like son -- butchers of Muslims".