SAO PAULO (Reuters) - Facebook owner Meta agreed to buy up to 3.9 million carbon offset credits from Brazilian investment bank BTG Pactual's forestry arm through 2038, the companies said on Wednesday in a statement.

They did not disclose the value of the deal. The average price for forestry carbon offsets last week was $4.22 per credit, according to data provider Allied Offsets. That could value the deal at up to $16 million based on that pricing.

Carbon offsets allow companies to offset greenhouse gas emissions by paying for actions to cut emissions elsewhere to meet corporate climate goals. Each credit represents a reduction of one metric ton of carbon dioxide emissions.

Under the long-term contract signed by Meta and BTG Pactual Timberland Investment Group (TIG), the owner of Facebook and Instagram agreed to buy 1.3 million carbon credits, with options to purchase an additional 2.6 million credits.

Meta said the deal is its largest carbon removal transaction from a single project and is part of its commitment to reach net zero emissions across its value chain in 2030.

The credits were generated by BTG Pactual TIG's forest restoration projects in Latin America, where it has planted more than 7 million seedlings, according to the statement.

In June, TIG announced the sale of 8 million carbon credits to Microsoft in the largest-ever transaction of such credits worldwide.

The deals from Microsoft and Meta come even though demand for offsets broadly stalled last year.

Companies including food giant Nestle and fashion house Gucci have reduced their buying of credits amid widespread doubts that they served to reduce emissions.

(Reporting by Andre Romani; Editing by Tom Hogue)