CARACAS (Dow Jones)--Venezuela's bolivar dropped toward its lowest level against the dollar in five months in unregulated trading Monday as traders said local companies began losing hope of getting the greenbacks they need at the cheaper, official rate.

A dollar was fetching about 6.45 bolivars in Venezuela's black, or so-called parallel market Monday, traders said, adding that the rate was very close to levels unseen since August. Some Web sites that track the unregulated market were quoting a rate of VEF6.52 per dollar Monday afternoon, which would be the bolivar's weakest level since Aug. 21, when it was at VEF6.54 for $1.

The government of President Hugo Chavez devalued the currency's official, pegged rate by half in early January, to VEF4.3 per dollar from VEF2.15 per dollar.

In doing so, the government indicated this would give it the ability to provide more local firms with the dollars they need at the official rate, and thus would reduce the need for black market trading.

"For the past month, there's been a wait-and-see attitude on the part of companies," said Russ Dallen, a trader at Caracas-based BBO Financial Services.

But, Dallen said local firms, many of which need hundreds of thousands of dollars at a time to pay for everything from auto parts to tires to foods that aren't made or processed in Venezuela, are having little luck meeting all those dollar needs through official channels.

As a result, they are once again being led back to the parallel market, which is driving up dollar demand and pushing down the value of the bolivar.

-By Dan Molinski, Dow Jones Newswires; 58-414-120-5738; dan.molinski@dowjones.com