Since the start of the conflict in Yemen in 2015, the UK reportedly sold £3.6bn in weapons to Saudi Arabia.
The campaign group Control Arms has produced a report which outlines the extent of arms sales by the UK, France and the US to Riyadh that have continued during a conflict in which an estimated 13,000 people have been killed since March 2015.
Oxfam says the UK should "stop the sales and push for a ceasefire" in the conflict that has wreaked damage and suffering on the Yemeni people, thousands of whom have been injured in hostilities.
Amnesty says the UK is supplying arms to the Saudis despite the risk of a violation of human rights.
The World Health Organisation and Yemen Health Ministry say over 600,000 people have been diagnosed with cholera which has killed over 2000 Yemeni people in the last four months.
The Saudis are supporting Yemeni president Abed Rabbo Mansour Hadi after Houthi fighters seized the capital Sana'a.
Lynn Maalouf, from Amnesty International's Beirut office said: "The USA and UK are fuelling serious violations that have caused devastating civilian suffering though multibillion-dollar arms transfers to Saudi Arabia that vastly overshadow their humanitarian efforts."
"Weapons supplied in the past by states such as the UK and USA have helped to precipitate a humanitarian catastrophe. These governments have continued to authorise such arms transfers at the same time as providing aid to alleviate the very crisis they have helped to create.
"Yemeni civilians continue to pay the price of these brazenly hypocritical arms supplies," the Independent reported.
Riyadh says it tries to limit civilian casualties is investigating incidents where civilians were killed.
It comes amid controversy over the Government's endorsement of the Defence Systems and Equipment International (DSEI) arms fair in east London this week, which has more than 35,000 visitors and exhibitors, including from the world's biggest arms companies.
Clarion Defence and Security, which organises the event says exhibitors comply with the UK Export Control Act so that equipment and services on offer comply with both UK and international law.