UPDATE 1-Australia's Viva Energy cuts H1 retail earnings guidance

* Sees H1 core earnings from retail unit of A$275 mln-A$290 mln

* That is down from April forecast

* Australia economy growing at slowest pace in a decade (Adds detail)

June 24 (Reuters) - Australian oil and gas company Viva Energy Group Ltd on Monday cut its half-year core earnings guidance for its retail segment, while its refining business was hit by weak regional profit-margins.

The company expects underlying core earnings from its retail business for the first-half of 2019 of A$275 million to A$290 million ($191 million to $202 million), lower than its outlook in April of A$286.9 million to A$291.9 million.

That comes days after rival Caltex Australia Ltd said it expected first-half profit to be less than half of what it was a year earlier, as the petrol station owner grapples with slowing economic growth and margin pressure.

"Soft regional demand continues to weigh heavily on regional refining margins," Viva Energy said in a statement.

Viva sees underlying earnings before interest, tax, depreciation and amortization for its refining business at about zero to A$20 million for the half. The company reported earnings of A$48.1 million at the same time in 2018.

The group's underlying net profit is expected to be about A$60 million to A$80 million in the half, compared with A$129.4 million a year earlier.

Australia, which has not reported a recession since the early 1990s, is growing at its slowest pace in a decade, with unemployment on the rise and consumer spending under pressure.

($1 = 1.4422 Australian dollars) (Reporting by Niyati Shetty in Bengaluru; Editing by Sam Holmes and Joseph Radford)