FINANCIAL MARKETS : Justice Dept. Nasdaq Probe Is Expanded : Investigation: The government asks dealers for detailed trading records and traders’ and supervisors’ compensation.

The Justice Department stepped up its investigation of Nasdaq stock market dealers by asking the firms for detailed trading records stretching back nearly a decade.

Securities firms that operate on the Nasdaq system said the federal agency wants records detailing their “payments for order flow,” or the money paid to other dealers in exchange for securities.

The Justice Department also wants traders’ phone numbers and is asking whether the firms recorded their phone calls. Firms were asked to disclose traders’ and supervisors’ compensation and the total number of Nasdaq stocks the firms bought and sold each year.

People at the firms called the requests for information excessive and said they’d probably be narrowed as the investigation continues. Moreover, few firms record telephone conversations, and are not legally bound to maintain records dating back 10 years.

As many as 30 large brokers that make markets in Nasdaq stocks recently received the civil investigative demands, which are 41-page documents. The demands signal that the government may be building a civil case against dealers, rather than a criminal case.

“No one is taking handcuffs out yet,” said Robert Skirnick, an attorney whose firm is representing shareholders charging Nasdaq securities dealers with collusion.

The government could still pursue criminal charges against dealers.

Nasdaq officials declined to comment on the latest round of requests for information, which were first reported in the Wall Street Journal on Wednesday.