Foreign Secretary William Hague today condemned the "shameful" rocket attack on a convoy carrying the deputy British ambassador to Yemen.
Fionna Gibb escaped unhurt from this morning's blast in the capital Sana'a, which injured one of her colleagues.
It is the second time in six months that British officials have been targeted in the country.
Tim Torlot, the then British ambassador to Yemen, was unharmed when a suicide bomber wearing a school uniform detonated an explosives belt in April.
In a separate incident today, a British man was injured and a Frenchman killed when a gunman opened fire at an oil company on the outskirts of Sana'a.
The Foreign Office said Mr Hague had received assurances from the Yemeni Government that a "vigorous investigation" would be carried out into the attack on the embassy vehicle.
Mr Hague said: "This shameful attack on British diplomats will only redouble Britain's determination to work with the government of Yemen to help address the challenges that country faces."
The armoured vehicle was in a convoy on its way to the embassy when militants opened fire, apparently using a rocket-propelled grenade.
Sources confirmed that Ms Gibb, deputy head of UK mission to Yemen, was in the car at the time but escaped unhurt.
Witnesses said two people were seen running away after the blast, leaving behind a bag containing parts of a weapon launcher.
A Foreign Office spokeswoman said: "The vehicle was on its way to the British Embassy, with five embassy staff on board.
"One member of staff suffered minor injuries and is undergoing treatment, all others were unhurt.
"We are aware of at least two bystanders injured during the attack."
The blast comes two days after Yemeni authorities boosted security around embassies in the capital after information about an attack planned by al Qaida.
Elsewhere in Sana'a, Austrian oil and gas company OMV said it could see "no political background" for today's attack by a Yemeni security guard that killed a Frenchman and injured a Briton.
A Foreign Office spokesman said: "We can confirm that a British national was injured in Sana'a. He has been hospitalised.
"We are in contact with OMV and stand ready to provide consular assistance."
Today's incidents have increased fears over the safety of westerners.
The attack on Mr Torlot's armoured car in April happened as he travelled through a neighbourhood in the eastern part of Sana'a, known to be popular with militants.
The bomber - a 22-year-old man - was killed.
It came after Umar Farouk Abdulmutallab - the man suspected of attempting to blow up a US-bound airliner on Christmas Day - reportedly told investigators that he was supplied with his bomb by al Qaida members in Yemen.
Nigerian-born Abdulmutallab's family have also suggested that he became radicalised during a visit last year to Yemen, where he was supposedly studying Arabic but is believed to have made contact with some of the estimated 300 al Qaida militants based in the country.