The chief executive of the UK's top Israel pressure group is to step down to "pursue new opportunities", after almost six years at the helm.

Former Labour MP Lorna Fitzsimons, below, will leave her role at the Britain Israel Communications and Research Centre (Bicom) next week. She led the team which launched the We Believe in Israel conference last year, attracting 1,500 people and more than 80 speakers from around the world.

But despite appointing a dedicated We Believe director, Luke Akehurst, this year's conference, due to take place in April, has been shelved, in favour of smaller, localised events.

Ms Fitzsimons took up her post in 2006, taking over from Israeli diplomat Danny Shek. The role of the organisation has largely been to counter anti-Israel propaganda and negativity in the media and the political arena, with many journalists and politicians visiting Israel on Bicom tours.

Ms Fitzsimons said: "I did not feel I could explore other opportunities while also devoting my full attention to the hugely demanding role of CEO, especially at this time of immense challenge and threat in the region. The organisation and the pro-Israel community need and deserve this focus from Bicom's CEO, and in all honesty I could not do that and review new roles at the same time. This decision has not been an easy one, but I think it is the right one at this time.

"To be able to work on an issue that you believe in and care about is a luxury not many people have. My belief in what we do and its importance has not diminished. Now, more than ever, Israel needs friends and I can assure you I will never stint in my efforts to promote and defend her."

Ms Fitzsimons's interim successor will be Dermot Kehoe, partner of the late chair of Labour Friends of Israel, David Cairns MP.

Bicom board chairman Poju Zabludowicz said the board had reluctantly accepted her resignation. He said that under Ms Fitzsimons Bicom had "excelled" in campaigning against boycotts of the state, and issues such as a nuclear Iran and Operation Cast Lead.

"Under Lorna's leadership Bicom has reached exemplary levels. She leaves a huge mark on the organisation, the pro-Israel community and Israel advocacy."

However, there were other less positive comments. One senior community figure told the JC that pro-Israel advocates in the UK and US believed it was time for a change in strategy from Bicom. One said: "Last time I was in Washington and mentioned Bicom to [US pro-Israel lobby group]Aipac representatives, they were surprised Lorna was still in position.

"If you do a survey which says a larger percentage of the British people hate Israel now than they did five years ago, clearly the strategy has not been working. To be very charitable, I would say nothing has been happening, and that Israel advocacy has got worse. It's time for change. Bicom should be focused on getting our community passionate, dynamic and loudly supportive."