By Katie Allen
BERLIN, Jan 30 (Reuters) - Germany's largest industrial union, IG Metall, staged short strikes across the country on Friday and called on 51,000 workers to leave work early in a mass walkout to pressure employers over pay and working hours.
IG Metall said short stoppages staged on Thursday had been stepped up to whole-day walkouts at some firms on Friday and that tens of thousands of engineering workers in the state of Baden-Wuerttemberg were set to down tools at 1300 GMT.
The union said the action would affect carmaker Audi as well as auto components groups Kolbenschmidt Pierburg and Robert Bosch [ROBG.UL].
Stoppages so far have targeted some major firms, particularly in the key automobile sector, such as at DaimlerChrysler AG but analysts say the short walkouts, a typical feature of German pay talks, will cause little pain to the firms.
"While the strikes could hurt sentiment on the stocks, the medium-term earnings impact of warning strikes is negligible. Overall, in a still weak economic situation the risk of a prolonged strike is rather limited," said analysts at one bank.
The IG Metall walkouts come after the union said it could not accept employer demands for longer working hours and an offer of less than half the four percent pay rise it is claiming for 3.5 million engineering workers.
In the state of Bavaria, where carmaker BMW and industrial giant Siemens are based, IG Metall said it would ask between 50,000 and 100,000 workers to walk out next Friday if employers do not present a new offer on Thursday.
In the central town of Stadthagen all-day strikes started at 0430 at various firms, including elevator maker Otis , a union spokesman said.
IG Metall spokeswoman Martina Helmerich said the stoppages would spread next week in defiance of claims the union's power had waned as a result of falling membership and a failed strike over working hours last year.
"The warning strikes so far have been successful and we see them as a signal that we are able to mobilise people. But we still want to get a result through talks," she said.
Talks in Baden-Wuerttemberg, which traditionally leads pay negotiations for the rest of Germany, are scheduled to resume next Thursday, February 5.
IG Metall this week dismissed as a "provocation" an offer from employers for two pay rises of 1.2 percent each over 27 months and a demand for more flexible contracts so firms can vary working hours to match demand.
Under negotiating rules IG Metall is allowed to stage short strikes to pressure employers during talks, provided the union gives the firms hit a clear start and end time. (Additional reporting by Madeline Chambers in Frankfurt)