By Andrew MacAskill and William James
LONDON (Reuters) - Britain has supplied Ukraine with Storm Shadow long-range cruise missiles, a Western official said on Thursday, which would allow its forces to hit Russian troops and logistics hubs deep behind the front line.
CNN first reported the decision, citing multiple senior Western officials. It said Britain had received assurances from the Ukrainian government that these missiles would be used only within Ukrainian sovereign territory and not inside Russia.
Ukraine has been asking for months for long-range missiles, but support provided by Britain and other allies such as the United States has previously been limited to shorter range weapons.
The Kremlin said the reports would require "an adequate response from our military".
Britain's defence minister Ben Wallace and the foreign minister James Cleverly have been in the United States for talks on supporting Ukraine in recent weeks.
Wallace is due to make a statement to parliament on Ukraine around 1100 GMT on Thursday.
The defence ministry in London declined to comment.
Britain and other Western countries have scaled up their military aid for Ukraine this year, with Britain saying in January it would send 14 of its main Challenger 2 battle tanks to Ukraine, a pledge that was followed by other nations including the United States and Germany.
The war in Ukraine is at a turning point, with Kyiv expected to unleash its new counteroffensive after six months of keeping its forces on the defensive, while Russia mounted a huge winter offensive that failed to capture significant territory.
Last week, a British-led group of European countries asked companies for expressions of interest to supply Ukraine with missiles with a range of up to 300 km (190 miles), but Britain said on Tuesday that no final decision had been taken on supplying the weapons.
The capabilities specified in that notice are in line with Storm Shadow missiles, manufactured by European missile maker MBDA, is an air-launched long-range missile, designed for attacks against high value targets such as hardened bunkers and key infrastructure, according to the company's website.
They have a range of more than 250 km (155 miles), according to the manufacturer.
Prime Minister Rishi Sunak told the Munich Security Conference in February that Britain would be the first country to provide Ukraine with longer range weapons.
The United States said in February it would provide the Ground Launched Small Diameter Bomb (GLSDB), which has a range of about 151 km.
Asked on Tuesday about supplying long range missiles, Cleverly declined to detail specific plans but he said it was important to keep looking at ways to "enhance and speed up the support we give to Ukraine".
(Reporting by William James and Andrew MacAskill; Editing by Kate Holton and Angus MacSwan)