(Reuters) - The FTSE 100 held steady as investors exercised caution in light of a new U.S.-EU trade tussle and ahead of a Brexit summit, while a U.S. indictment hit drugmaker Indivior and its former parent Reckitt Benckiser.
The FTSE 100 was marginally higher and the FTSE 250 was up 0.1 percent by 0731 GMT.
But markets were still subdued due to a transatlantic aircraft subsidy dispute, with the U.S. threatening to impose tariffs on $11 billion worth of European Union products.
Supermarket group Tesco rose 1.5 percent and was the biggest boost to the main index after a better-than-expected rise in full-year operating profit.
Gains were capped by a 3.5 percent fall in Reckitt Benckiser after the U.S. Justice Department accused its former unit Indivior of illegally boosting prescriptions for the film version of its blockbuster opioid addiction treatment Suboxone.
As a result, Indivior lost more than half of its value on the mid-cap index. Its shares, which have been pummelled by a protracted legal battle with India's Dr. Reddy's, were last seen down 53 percent.
Market participants also opted for a wait and watch approach ahead of a Brexit summit in which EU leaders are likely to grant British Prime Minister Theresa May a second delay to Britain's exit from the bloc, but could demand May accept an extension beyond June 30.
Mid-cap Dunelm rose 3.1 percent as a robust rise in third-quarter comparable sales helped the homewares retailer forecast full-year profit to top analysts view.
(Reporting by Shashwat Awasthi and Muvija M in Bengaluru; Editing by Angus MacSwan)
