STOCKHOLM, July 17 (Reuters) - Ailing airline SAS and pilot unions continued talks over new collective agreements on Sunday after negotiations through the night, a union representative told reporters as the strike entered its 14th day.

Most SAS pilots in Sweden, Denmark and Norway walked out on July 4 after talks over conditions related to the Scandinavian carrier's rescue plan collapsed. The parties returned to the negotiating table in the Swedish capital on Wednesday.

"We have been at it tonight and we continue," Norwegian pilot union representative Roger Klokset said while on a break.

Klokset said parties may have come closer to a deal overnight.

"Maybe. But I don't know whether there will be an agreement yet," he said.

SAS, the main owners of which are Sweden and Denmark, has been struggling to compete with low-cost competition for years before the pandemic slammed the industry. It needs to attract new investors and secure bridge financing, saying that it must first slash costs to achieve those objectives.

Pilots employed in the 75-year-old carrier's SAS Scandinavia subsidiary last week said they would agree to limited wage cuts and less favourable terms, but SAS said that concessions offered were not enough for it to carry out a rescue plan announced in February.

Unions also demand that pilots axed during the pandemic are rehired at SAS Scandinavia rather than having to compete with external applicants for jobs on less attractive terms at recently created SAS Link and Ireland-based SAS Connect.

On Saturday a mediator said the parties had made progress, but significant issues had yet to be resolved.

The airline said on Thursday that the strike had caused 2,550 flight cancellations, affecting 270,000 passengers and costing it between $94 million and $123 million. The Swedish government has said it will provide no more cash.

For Sunday, 164 SAS flights, or 62% of those scheduled, were cancelled, according to flight-tracking platform FlightAware. Pilots at SAS Link and SAS Connect are not on strike.

(Reporting by Anna Ringstrom Editing by David Goodman )