UPDATE 3-Panama ports strike ends, canal traffic normal

(Updates with strike over, canal authority comment, byline)

By Andrew Beatty

PANAMA CITY, Sept 2 (Reuters) - Workers ended a strike at two major ports at opposite ends of the Panama Canal on Tuesday and canal authorities said the day-long walkout did not noticably disrupt shipping through the waterway.

Crane operators and harbour towage workers at Balboa and Cristobal ports walked out in the morning, but union leader Luis Carlos Fruto said they later agreed to return to work after the government offered to help resolve a disagreement over pay for shift work.

"We have asked the labor ministry to arbitrate. Because of this, the strike has ended," Fruto told Reuters.

The labor ministry welcomed the swift end to the strike, saying prolonged action could have been "very negative" for the economy and for expansion work on the canal.

Shipping firms said earlier that roughly two-thirds of crane operators in Balboa and Cristobal ports were absent, leaving a backlog in loading and unloading containers.

Around 5 percent of global trade passes through the Panama canal, shipping everything from Chinese-made electronic goods to European farm produce, and the waterway accounts for a fifth of Panama's gross domestic product.

Some 60 harbor towage workers joined the strike, and the small number of tow boats operating could not match demand, shipping agents said. Ships cannot enter port unless they are guided in by tow boats, and the towage strike hit all types of cargo including non-containerized grains and commodities.