Toyota said Friday it expects global production to ramp up again by mid-year and return to normal by the end of 2011 after Japan's quake-tsunami disaster caused auto parts shortages.

Many key component manufacturers in Japan are based in the worst-hit northeast regions, where facilities were damaged by the 9.0-magnitude earthquake on March 11 or inundated by the giant wave that followed.

Toyota has announced production disruptions domestically and in the United States, European Union, China and Australia because of the crisis, temporarily shutting some plants or running them at half-capacity or less. On Friday it said it would also cut output in Thailand.

The world's biggest auto maker said in a statement that "global production will begin to ramp up as soon as July in Japan and August in North America, with all models back to normal production by November or December 2011".

"To all the customers who made the decision to buy a vehicle made by us, I sincerely apologise for the enormous delay in delivery," said Toyota president Akio Toyoda at a news conference in Japan.

Asked about the likely effect on the bottom line of the auto giant, Toyoda said only: "We have yet to comment on the impact on our profits. We want to tell you that at an appropriate time."

Toyota ended General Motors' 77-year reign as the world's largest automaker in 2008, but since then the Japanese giant has faced the impact of the global economic crisis, a massive safety recall crisis and a strong yen.

The company chief spoke about the impact of Japan's worst post-war disaster on the firm and the parts makers in its supply chain.

"Immediately after the earthquake, Toyota, like others, sent its employees into the disaster zone to join forces with our plants, dealers and suppliers to take steps toward recovery," he said.

"I too visited the affected areas several times. I saw people's efforts first hand, and I was filled with confidence that their hard work would make possible a quicker recovery of production."

He pledged: "Our entire company is committed to solving the problems before us, so that we can achieve production recovery even one day sooner."

Toyota's Japan plants are now working at 50 percent of capacity and those in North America at 30 percent because of parts supply shortages.

The company said it plans to continue procuring parts from the same suppliers, but will also consider substitute parts from other firms.

The auto maker said there are about new 150 parts now affecting new-vehicle production -- mainly electronic, rubber and paint-related. However, replacement parts for sales service and repair are available, it said.