National telecommunications company Spark is apologising to Dunedin residents for ongoing network problems.

Some Spark customers have had trouble with text messages for more than a week.

The problems started when Spark upgraded its software on the 20th of June.

That was supposed to improve text messaging, but instead some Dunedin users haven't been able to send or receive texts.

The company says it's working to fix the problem as soon as possible.

A spokesperson says the company's received a small number of queries about the issue.