Land covering an area the size of Italy has been taken from indigenous communities around the world by suppliers to the biggest names in the food and drinks industry, according to a major new report.

Coca-Cola and PepsiCo are among the companies criticised by Oxfam for their links to land disputes, with the charity alleging that nearly 800 large-scale land deals by foreign investors have seen 33 million hectares taken into corporate ownership globally since 2000.

The research – which also highlights alleged disputes with British food giant ABF – claims that poor communities from Brazil to Cambodia are losing their homes to make way for lucrative sugar crops to feed the rich world’s increasingly sweet tooth.

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Anti-poverty campaigners are now calling for major multinational companies to do more to stop indigenous communities from around the world from being forced from their homes.

Sally Copley, Oxfam’s campaigns director, said: “We need to be sure that what we eat and drink does not make the poorest and most vulnerable across the world homeless or landless. PepsiCo, Coca-Cola and ABF are the three big giants in the sugar industry and must lead the way in making sure we are not left with a sour taste in our mouths.”

Oxfam says the increasing appetite for sugar has gone largely unnoticed as a contributory factor to land grabs in the developing world. This is when local communities that rely on the land are evicted without consent or compensation – often violently – to make way for sugar plantations.

Oxfam links land disputes with companies that supply sugar for Coca-Cola products, including Coca-Cola, Sprite, Fanta and Dr Pepper. Pepsi-Co products implicated include Pepsi-Cola and Mountain Dew.

Oxfam’s report includes allegations that a fishing community on the Sirinhaem estuary in Brazil is fighting for access to their land after being violently evicted to make way for a sugar mill. The report claims the mill provides sugar to Coca-Cola and PepsiCo.

Meanwhile in south-west Brazil activists in Mato Grosso do Sul are fighting the occupation of their land by a sugar plantation supplying a mill owned by Bunge.

Coca-Cola admits it buys sugar from Bunge, but says it does not buy from this particular mill.

A Coca-Cola spokesman denied Oxfam’s allegations, saying: “Regarding the cases in Cambodia and Brazil, we sympathise with the citizens whose lives and livelihoods have been affected. While the Coca-Cola system does not buy sugar directly from any suppliers in Cambodia, we have agreed to convene a facilitated stakeholder dialogue to discuss Oxfam’s overall findings”.

A spokesman for PepsiCo said: “We have reached out to the suppliers; they have assured us they are in compliance with applicable laws. We continue to engage with our partners to further understand how they are addressing the issues raised by Oxfam.”

The report also highlights a Cambodian example in Sre Ambel. Former residents of the town are battling to win back land they claim to have been evicted from in 2006 to make way for a sugar plantation.

Oxfam alleges that the KSL-owned plantation supplies Tate & Lyle Sugars, which sells sugars to franchises that manufacture products for Coca-Cola and PepsiCo.

A Tate & Lyle Sugars spokesman said the firm only ever received “two small shipments” from KSL in Cambodia. They added: “The claims made against Tate & Lyle Sugars are disputed.”

The report also details links in media reports between ABF and cases of land conflict in Mali, Zambia and Malawi. A company spokesman said, “ABF, through its African subsidiary Illovo, is and always has been hugely sensitive to issues of land ownership… throughout its operations in Africa, Illovo has been scrupulous in its approach to land ownership.”