The English Defence League, a far-right grouping aimed at combating the "Islamification" of British cities, has developed strong links with the American Tea Party movement.

An Observer investigation has established that the EDL has made contact with anti-jihad groups within the Tea Party organisation and has invited a senior US rabbi and Tea Party activist to London this month. Rabbi Nachum Shifren, a regular speaker at Tea Party conventions, will speak about Sharia law and also discuss funding issues.

Devin Burghart, vice-president of the Kansas-based Institute for Research & Education on Human Rights, said: "Geller is acting as the bridge between the EDL and the Tea Party. She plays an important role in bringing Islamophobia into the Tea Party. Her stature has increased substantially inside the Tea Party ranks after the Ground Zero mosque controversy. She has gained a lot of credibility with that stuff."

The Tea Party is expected to be an influential force in America's mid-term elections. Last month their candidate Christine O'Donnell romped to the Republican nomination in Delaware, following a stream of populist rightwing candidates who carry the movement's s****. Burghart says anti-Islamic tendencies have become far more marked in the grassroots organisation: "As we move farther and farther away from the Tea Party origins, that were ostensibly around debt and bail-outs, social issues like Islamophobia are replacing that anger, that vigour. The idea that there is a war between Islam and the west is becoming commonplace."

With the Tea Party said to benefit from millions of dollars of funding from conservative foundations, experts warn an alliance between the EDL and extremist elements within the US movement could allow the English group to invest in wider recruitment and activism.