Oil prices were mixed on Thursday, coming under pressure from evidence of rising U.S. output and uncertainty over the outlook for supply before a meeting next week of the world`s largest exporters. U.S. West Texas Intermediate (WTI) crude futures ended Thursday`s session up 25 cents at $66.89 a barrel. Brent crude futures was down 86 cents, or 1.1 percent, at $75.88 a barrel shortly before Thursday`s settlement. The Organization of the Petroleum Exporting Countries and other big producers meet on June 22-23 in Vienna to discuss production and are widely expected to agree to higher output. Russian Energy Minister Alexander Novak told reporters that members of the OPEC-plus production cut deal can consider returning up to 1.5 million bpd to the market gradually. Saudi Energy Minister Khalid al-Falih said he expected a reasonable and moderate agreement next week when OPEC and non-OPEC oil producers meet.