July 28 (Bloomberg) -- Nigeria's main militant group in the oil-rich Niger Delta region said it sabotaged two pipelines today in Rivers state after vowing last week to renew attacks.

The Movement for the Emancipation of the Niger Delta, or MEND, believes the pipelines, located in Kula and Rumuekpe, are operated by a unit of Royal Dutch Shell Plc, the group said today in an e-mailed statement. The attacks occurred at 1:15 a.m. local time, MEND spokesman Jomo Gbomo said in the statement.

The action was ``in keeping with our pledge to resume pipeline attacks within the next 30 days,'' the group said. MEND threatened on July 23 to renew assaults on pipelines after calling a cease-fire a month earlier to give regional officials time to negotiate an agreement with the government. Militant attacks have halted about 20 percent of Nigeria's oil production since 2006 and helped raise crude prices to records.

Shell Petroleum Development Co., the company's local unit, confirmed an incident occurred on the Nembe Creek trunk line around the Kula area of Rivers state.

``A helicopter overfly today confirmed that parts of SPDC's Nembe Creek trunk line were damaged in attacks,'' Shell spokesman Rainer Winzenried said in an e-mailed statement. ``We are working to ascertain the extent of damage, and have shut in some production to limit the amount of crude that will spill into the environment.''

Yar'Adua Claims

MEND vowed to renew attacks after local newspapers reported claims by Nigerian National Petroleum Corp. head Abubakar Yar'Adua that the government had paid militants millions of dollars to gain access to repair a crude pipeline.

Lieutenant Colonel Sagir Musa, the spokesman for a military task force in charge of security in the Niger Delta, today denied any attack took place in the locations cited by MEND.

``Nothing happened'' in these areas, Musa said, adding that the Nembe Creek trunk line is in a different part of the state.

The Nembe Creek line was last attacked on May 26, leading Shell's Nigeria venture to declare ``force majeure'' on Bonny Light crude exports for June and July. Force majeure is a legal clause that allows producers to miss contracted deliveries because of circumstances beyond their control.

The company previously declared a delay on 130,000 barrels a day of Bonny Light crude exports from the trunk line in early February after failing to repair damage detected in January. That force majeure declaration was lifted March 3.

Oil Gains

Crude oil for September delivery gained as much as $1.96, or 1.6 percent, to $125.22 a barrel today in electronic trading on the New York Mercantile Exchange. It was at $124.48 a barrel as of 1:41 p.m. London time.

Separately, five Russian oil workers kidnapped last week from the vessel Herkules off Nigeria were freed today, Reuters reported, citing an unidentified state security official. Musa was unable to confirm the report.

Eight other expatriates, including three Russians, four Lithuanians and one Latvian, were freed yesterday without ransom, one day after being abducted, ThisDay newspaper reported.

To contact the reporters on this story: Karl Maier in Rome at kmaier2@bloomberg.net; Julie Ziegler in Lagos at jziegler@bloomberg.net.

Last Updated: July 28, 2008 09:00 EDT