UN chief Ban Ki-moon is alarmed by the mounting crisis pitting Colombia against its neighbours Venezuela and Ecuador and is calling for restraint, his press office said on Monday. 'The Secretary General is concerned about the increased tensions and heightened rhetoric emerging over the weekend involving Colombia and its neighbours, Ecuador and Venezuela,' a UN statement said. 'He urges restraint and calls on all three countries to address their shared concerns in the spirit of dialogue and cooperation that has traditionally characterized their relations,' it added.