Exclusive - Shell CEO warns Brexit could slow $30 billion asset sale plan

By Ron Bousso and Freya Berry LONDON (Reuters) - Royal Dutch Shell's chief executive, Ben van Beurden, has told investors that Britain's decision to exit the European Union could slow its $30 billion (23 billion pounds) asset sale plan, especially in the North Sea which had struggled to attract buyers for years. The comment, made during an investor and analyst event at the Wimbledon tennis tournament this week, came as Shell mandated Bank of America Merrill Lynch to find buyers for several key a