By Matthew Chapman
Tear gas has proved deadly in Zimbabwe
Britain faces embarrassment over claims that Malawi, a major recipient of UK aid, is involved in flouting Western sanctions in supplying the Zimbabwean police force with tear gas.
The tear gas has been linked to at least 11 deaths, including those of five babies during a single incident in Zimbabwe.
The BBC has learnt from diplomatic sources that the Department for International Development (Dfid) has launched investigations into the allegations.
But Dfid has denied the claim and the Malawian government said the allegations were "malicious".
Tears and coughing
Reports from human rights organisations say tear gas has been in use in the last two weeks in Zimbabwe as police arrested 22,000 people as part of what they say is a crackdown on illegal traders.
The worst recorded incident occurred last September.
Eleven people were killed when Zimbabwe riot police moved in to evict what was claimed to be an illegal settlement numbering up to 15,000 people in Porta Farm on the outskirts of the capital, Harare.
It is thought to be the largest-ever number of deaths attributed to tear gas.
In several sworn affidavits given to human rights investigators, residents describe how police began firing tear gas canisters into their homes.
One man was eating porridge in his courtyard with a friend when a canister landed.
"Three tear gas canisters were fired and exploded within the yard causing everyone to shed tears and coughing," he said.
"I ran for my life and left him inside the house. Upon my return I found him dead.
"His body was at the door - maybe he was trying to come out for free air."
Among the deaths reported to local police were those of five babies under the age of one, including a baby only one day old.
The UK led the way in getting the European Union and the US to impose a ban on sales of tear gas to Zimbabwe in 2002 after the police were implicated in a pattern of human rights abuses.
Zimbabwe police still obtain tear gas despite a ban on sales
However, the Zimbabwe police have continued to obtain stocks of tear gas.
A British diplomatic source has told the BBC there is increasing evidence pointing to the involvement of near-neighbour Malawi in a trade in tear gas which has close links to Zimbabwe.
Fears were first raised last year when the Foreign Office learned that the Malawian government was in the process of buying £500,000 ($907,000) of tear gas.
Such a large order from a country which ranks as the 10th poorest in the world rang alarm bells, said the source, who would not be named because of his close association with Dfid.
"The Malawian police would only ever need a tiny amount to use in riots and demonstrations, so the idea of them buying such huge quantities of it threw the Dfid people into a bit of a panic," he said.
It is understood the British High Commissioner to Malawi wrote a letter to the government complaining about the purchase. The Foreign Office has refused to comment.
British officers have helped to train Malawian police in the use of tear gas and the UK department has spent more than £30m ($54m) on the Malawian police and courts system.
Although it is not thought that any British aid money was directly involved in the purchase, local Dfid staff apparently fear the Malawian government may be using "backfilling".
The practice involves the diversion of the government's own money earmarked for development projects followed by the use of British aid money to fill the financial void.
Amnesty backs claims
Human rights group Amnesty International has backed up the claims by issuing a statement saying that it has also gathered evidence of an operation which in effect breached Western sanctions.
The group says it has received "recent reports" that tear gas has been stocked in Malawi ready for supply to Zimbabwe.
Amnesty is calling on several governments including the UK and US to launch an inquiry into the claims.
Matthew Chapman's programme The Five Live Report: Gas Attack can be heard on BBC Radio Five Live at 1000 GMT on 5 June 2005 and from that time at the Five Live Report website.