The United Arab Emirates suggested it might withdraw intelligence cooperation with the US in an attempt to block legislation allowing families of September 11 victims to sue Saudi Arabia and UAE for compensation.

Leaked emails seen by the Telegraph show how Yousef Al Otaiba, the UAE's ambassador to Washington DC, privately warned senators that countries at risk of being sued in US courts would be "less likely to share crucial information and intelligence".

The communications reveal how UAE joined Saudi Arabia's work to lobby against the Justice Against Sponsors of Terrorism Act (Jasta), with Mr Al Otaiba coordinating his efforts with Adel al-Jubeir, the Saudi foreign minister.

Two of the 19 hijackers who flew planes into the World Trade Center towers in 2001 came from the UAE while 15 others were Saudi.

Court documents filed in New York show that after Jasta was passed, a legal claim was launched against UAE's Dubai Islamic Bank, in which it was alleged that the Bank "knowingly and purposefully provided financial services and other forms of material support to al Qaeda ... including the transfer of financial resources to al Qaeda operatives who participated in the planning and execution of the September 11th attacks."