With throngs of backers so thick they spilled out the doors of a massive committee hearing room here, supporters and opponents fought out the first round of the "bottle battle": proposed legislation to require deposits on bottles and cans.

Environmental and conservation groups squared off against an amalgam of unions and the can and bottle industry, each side trying to garner a majority vote on a House of Delegates committee that can move the measure along to the full body or kill it.

The bill would require a 10-cent deposit on most bottles and cans. If the industry designed a uniform bottle that could be used interchangeably by various companies, it would require a 5-cent deposit. The legislation also bans pop-tops and the plastic six-pack ring carriers. It would set up redemption centers for the bottles and cans.

The legislation would save 4.3 trillion BTU's of energy annually in Maryland, enough to heat 30,000 homes, the backers told the 24-member Environmental Matters Committee.

Spouting his own set of figures, the president of the Maryland AFL-CIO argued taht the measure would not solve solid waste problems -- as proponents contend -- because disposable beverage containers represent only 5 percent of these wastes.

One of the most influential lobbyists in Annapolis, James J. Doyle Jr., representing the Glass Packaging Institute, rose to speak.

"I've listened to all the arguments on both sides, and I'm convinced it's the same as the cases I argue in court. If you need an expert witness, and you've got enough money to spend, sooner or later you'll bet one who will say what you want to hear."

So it went, in what promises to be one of the hottest lobbying wars in Annapolis this year.

Proponents, including Del. Gerald W. Winograd (D-Anne Arundel), the House bill's chief sponsor, stressed energy savings the measure would provide and decreases in solid wastes.

Opponents talked of threatened loss of jobs in the can and bottle industry, and argued that proposed litter recycling laws would more effectively fight the solid waste problem.

Similar laws have been passed, after major battles between environmentalists and a coalition of labor and industry, in six states. A seventh, Delaware, has passed a mandatory deposit law that will go into operation only if its neighbors, Maryland and Pennsylvania pass similar measures.

Each side in the fight has attempted to gain the support of Gov. Harry Hughes, who thus far has been noncommittal.