Britain's arms sales to Bahrain are under urgent review following violence there, the Foreign Office has said.
It said 250 cartridges of tear gas and other riot control equipment had been licensed for export to the Gulf state within the past nine months. The foreign secretary said there was no evidence UK tear gas was used in the military crackdown on protesters.
Four people were killed in Bahrain on Thursday after riot police attacked anti-government demonstrators.
'Human rights abuses'
William Hague told the BBC a review requested on the issue of future export criteria to Bahrain was expected to report back on Friday. The UK had some of the strictest export criteria in the world, he added.
Asked what message he had for Bahrain's government, he said: "Dialogue with the opposition forces in Bahrain is extremely important and must be recommenced at the first opportunity.
"And that dialogue ought to lead to further reforms in the political system and respond to legitimate grievances."
Britain's arms export licences could be revoked if they are found to have breached UK and EU export criteria.
Earlier, foreign office minister Alistair Burt said: "We will not authorise any exports which, we assess, might provoke or prolong regional or internal conflicts, which might be used to facilitate internal repression, or which would in any other way be contrary to the criteria."
He said "in light of events" he was "formally reviewing recent licensing decisions for exports to Bahrain".
"We will urgently revoke licences if we judge that they are no longer in line with the criteria," he added.
Earlier on Thursday, Labour MP Denis MacShane told the Commons governments of all parties had "turned a blind eye to the repression and corruption" of autocratic regimes in the Middle East.
Mr Hague told the Commons that, in a conversation with Bahrain's foreign minister, he had stressed the need for peaceful action in dealing with the protesters.
The Foreign Office is advising British nationals to stay away from protests and avoid all but essential travel around the island.