LONDON — Britain is involved in military contingency planning with the United States over Iran and other potential flashpoints in the Middle East, officials said Friday, but they insisted the talks aren’t a prelude to a preemptive strike against Tehran’s nuclear program.

Prime Minister David Cameron’s office confirmed that routine military planning is being carried out with the United States and other allies on a range of scenarios, including on the potential use by American forces of British bases, some of which can act as staging posts for missions to the Middle East.