A second straight day of direct negotiations aimed at resolving the postal contract dispute produced no progress yesterday as the slow-paced talks moved toward a Sept. 16 deadline.

"Nothing really spectacular is happening, and we don't expect anything much to happen for awhile," said one source close to the talks between the Postal Service and three unions representing 516,000 workers.

The talks are being held amid renewed threats by local union leaders to stage a mail strike if a satisfactory agreement is not produced.

But some national union officials recently have been calling the strike threats exaggerated, contending privately that few of the nation's postal workers would participate in a walkout, barred by federal law.

A proposed settlement reached July 21 was rejected by union members last month, forcing union leaders to call a nationwide walkout, averted when the Postal Service agreed to a unique 15-day round of bargaining with a special mediator.

The bargaining officially began last Friday, but bargainers spent the Labor Day weekend meeting separately with the mediator, Harvard labor relations professor James Healy, and did not begin face-to-face negotiations until Tuesday.

The two sides have little to talk about: the unions want a bigger pay raise, which is opposed by management; management wants to weaken a clause barring worker layoffs, which is opposed by the unions.