Charity calls for new international treaty on arms trade, which it says is less tightly regulated than trade in bananas or coffee

The Syrian government imported $167m-worth of air defence systems and missiles and a further $1m of small arms and ammunition in the months before it began a crackdown on opposition activists, a report claims.

The charity Oxfam says the sale and transfer of munitions to President Bashar al-Assad's regime in 2010 highlights the need for a new international arms trade treaty. The treaty would provide "clear, unambiguous, legal obligations on states" not to sell weapons if they might end up being used to provoke conflict or violate human rights.

The EU imposed an arms embargo on Syria in May last year, but France has accused Iran of continuing to sell weapons to Assad. Russia is known to be a major exporter of arms to Syria.

In its report, The Devil is in the Detail, Oxfam says that between 2000 to 2010 more than £2.2bn worth of weapons and ammunition were bought by countries that were the subject of 26 different arms embargoes.

A UN conference in July could lead to a new treaty that would harmonise and, where necessary, toughen up laws governing the sale of arms "into one comprehensive, legally binding instrument".

Oxfam argues that the trade in weapons is less tightly regulated than that in consumer goods such as bananas, coffee and cocoa.

Anna Macdonald, head of Oxfam's control arms campaign, said: "How can the sale of bananas be more tightly controlled than the sale of machine guns? It just doesn't make sense. This situation is indefensible and it's long overdue for countries to hammer out a legally binding agreement on weapons transfer.

"We are on the brink of a historic moment but the challenge is to ensure the new treaty is really strong. It must unambiguously stop arms transfers where they would fuel conflict, poverty or human rights abuses. Existing arms embargoes are far too easy to break or ignore. The lack of international regulation means that states under embargo have been importing whatever weapons they choose with impunity."

Oxfam claims that in the first decade of this century, several states broke embargoes and continued to trade weapons on a large scale. The report cites Burma ($600m between 2000-2010), Iran ($574m between 2007-2010) and the Democratic Republic of the Congo ($124m between 2000-2002).

The charity obtained the figures by trawling through data held by the independent Stockholm International Peace Research Institute (Sipri) and the United Nations commodity trade statistics database.

Macdonald said a new treaty had to be "robust enough to have a genuine impact on the lives of tens of thousands of innocent civilians suffering from armed violence every single day".

"This is the chance of a generation to truly make a difference. A weak treaty would be worse than no treaty at all as this would merely legitimise the existing flawed system."

The global weapons market is estimated to be worth $55bn, and the UN Office for Disarmament Affairs states that the "trade in conventional weapons – from warships and battle tanks to fighter jets and machine guns – remains poorly regulated. No set of internationally agreed standards exist to ensure that arms are only transferred for appropriate use."

Some countries, such as Russia and China, have lobbied for diluting the language of any new arms trade treaty, particularly over the banning of weapons sales if there is reason to think they might be used to violate human rights. Although supportive of a new treaty in principle, the White House has also raised concerns, saying that if it is too prescriptive many nations will be deterred from signing.

Last year, the British Foreign Office minister Alistair Burt said the treaty had "the potential to prevent human rights abuses, reduce conflict and make the world a safer place".