SYDNEY, Aug 28 (Reuters) - New Zealand has asked the country's communications security bureau to help bourse operator NZX Ltd after it crashed for the fourth day in a row on Friday, Finance Minister Grant Robertson said.

"I can't go into much more in terms of specific details other than to say that we as a government are treating this very seriously," Robertson said in a media briefing in Wellington.

The bourse operator said its networks crashed due to connectivity issues relating to two cyberattacks targeted at them this week. (Reporting by Renju Jose; Editing by Jacqueline Wong)