Adds comments and outlook from conference call in paragraphs 3, 4, 10, 11, 12, 13; shares in paragraph 5

By Arathy Somasekhar and Tanay Dhumal

July 22 (Reuters) - Oilfield services company Halliburton HAL.N forecast a sharp decline in full-year revenue on Tuesday after posting a 33% fall in profit for the second quarter due to softer-than-expected demand.

Houston-based Halliburton joined larger rival SLB SLB.N in warning of lower activity by oil and gas producers as weak and volatile oil prices have led producers to curb capital spending and drilling. Oil prices have decreased by about 8% over the last year.

"To put it plainly, what I see tells me the oilfield services market will be softer than I previously expected over the short to medium term," CEO Jeff Miller said on an earnings call.

North American producers are planning meaningful scheduled gaps in drilling and completions activity in the second half of 2025, while international customers continue to reduce activity and lower discretionary spending, reflecting much lower commodity prices, Miller added.

Shares of the company were down 0.7% at $21.03. They are down nearly 23% year-to-date.

"We had previously believed the worst was over for oilfield services, but HAL's cautious commentary gives us pause," said Stewart Glickman, energy equity analyst at CFRA Research.

The company said President Donald Trump's tariffs cut profit by $27 million in the second quarter and expects a $35-million, or four cents per share, hit in the third quarter.

North America revenue tumbled 9% to $2.26 billion in the quarter, while international revenue eased 3% to $3.25 billion.

Full-year North America revenue will decline by the low-double digits year-over-year due to lower drilling and completions activity, Halliburton said.

"Customers are fairly cautious in conserving their budgets, Miller said, citing reorganizations and cost-reduction efforts by large producers and major oil companies."

International revenue in 2025 is expected to contract by mid-single digits, year-over-year, primarily due to less activity in Saudi Arabia and Mexico, the company said. It had previously forecast international revenue to be flat to slightly down.

Rival SLB also flagged weaker drilling activity in Saudi Arabia and Latin America last week.

Halliburton said it will retire, idle, or reallocate underperforming assets such as equipment and fleets to cut costs.

The company's quarterly revenue fell 5.5% to $5.51 billion from a year earlier, but was higher than Wall Street estimates of $5.41 billion, according to data compiled by LSEG.

The company reported profit of $472 million for the quarter ended June 30, down from $709 million a year earlier. On a per-share basis, Halliburton posted in-line earnings of 55 cents.

(Reporting by Tanay Dhumal in Bengaluru; Editing by Sriraj Kalluvila and Rod Nickel)

((Tanay.Dhumal@thomsonreuters.com; Twitter: https://twitter.com/TanayDhumal;))