Prime Minister Gordon Brown is making a fresh attempt to secure international agreement for extended EU sanctions against Robert Mugabe's regime in Zimbabwe.
He will use the launch of the Mediterranean Union in Paris to raise the issue with fellow European leaders, including French President Nicolas Sarkozy and European Commission President Jose Manuel Barroso.
It follows Friday's vote in the United Nations Security Council when Russia and China used their vetoes to block a worldwide sanctions package, including an international arms embargo.
Mr Brown now wants to work through the EU to expand the current travel ban on leading regime figures and to take measures against companies owned by them.
The gathering of the Mediterranean Union will bring together around 40 heads of government from across Europe, North Africa and the Middle East.
It is designed to cement partnership between the EU and the countries bordering the Med, and is seen as a key pillar of French president Nicolas Sarkozy's six-month presidency of the EU, which began on July 1.
Attention is likely to be focused on Israeli prime minister Ehud Olmert and Syrian president Bashar Assad, who will be around the same table for the first time. With no high-level contact between the countries since 2000, observers say that a handshake - let alone a meeting - between the two men would mark considerable progress in Israeli-Syrian relations.
Lebanon's new president Michel Suleiman is expected to hold talks with Mr Assad, and said he hoped to see a restoration of diplomatic relations, broken off in 2005 after the murder of Lebanese prime minister Rafik Hariri. Beirut suspects its larger neighbour of a role in the killing, something which Syria denies.
The scope of the new Union has been significantly scaled back since Mr Sarkozy first floated the idea during last year's presidential campaign as "a great dream of peace and a great dream of civilisation".
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His proposal for a Mediterranean Union, complete with its own investment bank and regular ministerial meetings and open only to those countries with a coastline on the Med angered Germany. To appease Berlin, membership was widened to include all 27 EU states, along with 17 from north Africa and the Middle East.
