ALBANY – The gulf between Senate Republicans and Assembly Democrats on the issue of civil confinement of sexual predators appeared to expand yesterday,as the two sides lashed out at each other during a joint conference committee intended to bridge differences.

Arguing over the details of legislation that would permit the state to detain convicted sexual offenders in mental facilities indefinitely after their prison terms, Senate Republicans accused the Democrats in the Assembly of inserting a loophole into their version of the bill that would render it powerless.

In the Assembly’s bill, if a jury finds the respondent to be a sexual predator, a disposition hearing is held to determine whether the offender ought to be locked up in a ward or be sentenced to “strict and intensive” supervision. Under the Democrats’ plan, a jury would opt for supervision if it determined that such treatment would likely deter the person from committing a sex crime.

The Senate version does not make available the supervision option, which Democrats likened to giving a jury in a murder trial the choice of recommending the death penalty or life without parole. Republicans retorted that the comparison was telling, as New York hasn’t executed anyone since 1960.

Toward the end of the two-hour session, the second joint conference on the bills, Martin Golden, a Republican senator of Brooklyn and a former New York City police officer, raised his voice and looked incredulously at Democrats at the opposing end of the hearing room conference table. “I don’t know why we’re coming to this meeting,” he said. “I don’t want to waste my time when we know we’re going to get a deal-breaker. In your bill nobody gets confined.”

Democrats expressed their own concerns, about certain nonviolent sex crimes, and asked whether an 18-year-old having sex with a 14-year-old, should trigger sexual confinement trials. They also said they feared that the Republican legislation would encourage prosecutors to search for sexual motives in non-sex crimes, such as burglary, arson, and robbery, so suspects could become eligible for sexual confinement.

“My fear is that we’re going to have a witch hunt,” Peter Rivera, a Democrat of the Bronx who heads the Assembly’s committee on mental health, said.

Mr. Golden said there needs to be a provision in the bill that would allow the state to confine a person who broke into an apartment and raped a woman but was convicted only on the burglary charges. Several Republicans also demanded the Assembly amend its bill so that people who commit sex crimes before turning 18 could be confined.

Senator Dale Volker said a child who has “committed 50 rapes by the time he’s 13” ought to be considered for civil confinement.

One Senate Democrat, Thomas Duane of Manhattan, said both bills are flawed and raised doubts about the process for deciding whether a crime is sexually motivated. “How do you get into the person’s head to find out whether it’s sexually motivated?” he asked. “I’m not saying don’t do anything, but let’s be smart and constitutional when we do this.”

He accused Republicans of ignoring how the sexual predators would be treated for a mental illness during confinement, saying the lawmakers’ intention is simply to lock them up for life.

While the Senate has passed civil confinement bills every year since 1998, this is the first year the Assembly has approved a version of the legislation. The bills were introduced last month, as Governor Pataki proposed in his budget to spend $130 million to tear down a minimum-security correctional facility in Chenango County and build a 500-bed facility for sexual predators.

The Supreme Court in 1997 upheld civil confinement for sexual predators, and more than 15 states have approved laws similar to the ones New York lawmakers are proposing.