By Cassie Werber

Oil is down Tuesday morning amid plentiful supply and despite the political tensions in Ukraine and the Middle East.

High supply levels will continue to preclude any marked increases in price, said analysts at Commerzbank. "In Libya, for instance, oil production is continuing to normalize gradually despite ongoing fighting and growing political chaos," they wrote in a note to clients.

Among the most alarming developments: Libya's outgoing cabinet has acknowledged that it has lost control of the capital Tripoli to Islamist-allied militias, risking oil production that averaged around 500,000 barrels a day at the end of August.

Yet oil markets have barely reacted, although Commerzbank noted that speculative financial investors increased their net long positions in Brent by 1,000 contracts in the week to Aug. 26, betting that the price would go up.

"This was the first position build for four weeks and only the second in the last nine weeks. During this time, speculative net long positions have plummeted by more than 70% to a two-year low, which doubtless exacerbated Brent's price slide in July and August," they wrote.

This morning, though, Brent crude oil for October delivery is down 88 cents at $101.89 a barrel on ICE Futures Europe. October WTI is down 70 cents at $95.27 a barrel on the New York Mercantile Exchange.

U.S. markets will reopen after the Labor Day holiday weekend, and investors are likely to assess recent developments in Ukraine and Libya, and manufacturing and economic data from different countries, traders said.

In Ukraine, the military is moving to adopt a defensive strategy against an incursion by Russian troops, even as U.S. and European officials discuss a fresh round of sanctions against Moscow.

Gasoil for September delivery is down $5.00 at $858.50 a metric ton on ICE futures Europe. Gasoline for October is down 325 points at $2.5909 a gallon.

-Eric Yep in Singapore contributed to this article.

Write to Cassie Werber at cassie.werber@wsj.com

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