LONDON (Reuters) - British Prime Minister Theresa May will speak to U.S. President Donald Trump on Tuesday to discuss North Korea, her spokeswoman said, after it conducted its sixth and largest nuclear test two days ago.  She is due to speak to President Trump shortly,  her spokeswoman told reporters, adding that May also planned to speak to French President Emmanuel Macron about North Korea.  Earlier, a British minister summoned the North Korean ambassador to the foreign ministry to condemn the test on Sept. 3. 