The British security corporation G4S today faces heavy pressure to end its contracts with Israel's prison system amid new claims over the provision of equipment to jails where Palestinians are illegally detained without charge or trial.

The accusations come from Randa Wahbe, advocacy officer for the Ramallah-based Addameer Prisoner Support and Human Rights Association.

Wahbe tonight starts a tour of Britain to step up the campaign against G4S's complicity in Israel's violations of international law.

Wahbe will cite testimonies from Palestinians who, after starting hunger strikes, were put in cold, tiny cells and denied blankets - with only a pit in the floor to relieve themselves - and monitored round the clock by G4S-supplied cameras.

As the Israeli Prison Service seeks fresh legislation to allow force-feeding of hunger strikers, Mo'ammar Banat and Akram Fasisi, held at Israel's Ramleh jail under indefinite orders, suffer night raids, searches and are denied family visits.

Both reported that despite the strikes causing breathing difficulties and exhaustion Israeli officers shackle their hands and feet to prison hospital beds and sometimes move them to solitary confinement as punishment for their defiance.

Wahbe's talks on campuses with G4S contracts will come just over a year after a Palestinian detainee died following alleged torture at a prison whose security system and central control room were supplied by the British company.

Arafat Jaradat was found dead at Megiddo prison in the wake of claims that Israel's security service beat him during interrogation at al-Jalameh prison, which, like Megiddo, is located in Israel.

According to article 76 of the UN Fourth Geneva Convention, governments must not transfer prisoners from occupied territory into the territory of the occupier.

The universities Wahbe will be speaking at are already under pressure to cancel their G4S contracts after King's College London and Southampton University dropped the company in November.

Wahbe will speak out during Israeli Apartheid Week, in which events around Britain and overseas promote the Boycott, Divestment and Sanctions movement against the illegal occupation of Palestine.

Her first meeting takes place this evening at Kent University, with others later this week at University College London, Durham University, Edinburgh University and Dundee University.

The opening event comes just days after news that Kent University student union plans to terminate its present cash handling services contract with G4S and is holding a referendum on whether to launch a campaign to press the university to cancel its own contract with the company.

In the second meeting, at University College London, the audience will also hear from South African former anti-apartheid activist Salim Vally, who helped lead the successful drive that saw Johannesburg University, where he works as a senior researcher, join the academic boycott against Israel. In addition, G4S provides security systems at another Israeli prison, Ketziot.

The firm also provides equipment for Ofer prison, located in the occupied West Bank, and for Kishon and Moskobiyyeh detention facilities, at which human rights organisations have documented systematic torture and ill treatment of Palestinian detainees, including child prisoners.

Beyond Israel's prison system, G4S also provides equipment and services to Israeli checkpoints in the West Bank that form part of Israel's illegal wall and to the terminals isolating Gaza's occupied and besieged territory.

Moreover, the multinational has signed contracts to provide equipment and services for the Israeli police headquarters in the West Bank and to private businesses based in illegal Israeli settlements.

The Boycott, Divestment and Sanctions movement against Israel's occupation has received global endorsement, including from the African National Congress, the organisation which led the successful fight against South African apartheid.

The late Nelson Mandela, the ANC leader who spearheaded the struggle to end apartheid, said that "our freedom is incomplete without the freedom of the Palestinians."

Among the British public figures who have backed the movement is physicist Stephen Hawking, who joined the academic boycott drive when he pulled out of a conference hosted by Israeli President Shimon Peres in Jerusalem.

The cultural boycott of Israel has won support from British solo musicians Roger Waters, Annie Lennox, Elvis Costello and Brian Eno, the bands The Klaxons, Gorillaz Sound System, Leftfield and Faithless, as well as film-makers Ken Loach and Mike Leigh.

The Kent University meeting begins at 6pm in Rutherford lecture theatre 1, University Road, Canterbury CT2 7NZ; the University College London event is at 7pm on Wednesday in Room B40 at the Darwin building, Gower Street, WC1E 6BT; the Durham University meeting starts at 7pm on Thursday in room CG85 at the chemistry department, South Road, Durham DH1 3LE; the Edinburgh University event is at 7pm on Friday in lecture theatre 183 at Old College, South Bridge, Edinburgh EH8 9YL and the Dundee University meeting begins at 2pm on Saturday in the D'Arcy Thompson lecture theatre at the Tower Building, Perth Road, DD1 4HN.