(Corrects paragraph 4 to say delivering vehicles and revenue, not the plan, are crucial for Nissan's comeback)

By Daniel Leussink and Maki Shiraki

TOKYO (Reuters) -Japan's Nissan has started offering buyouts to U.S. workers and has suspended merit-based wage increases worldwide, internal emails reviewed by Reuters showed, as the automaker expands cost cuts amid weak performance in key markets.

CEO Ivan Espinosa announced a new round of cost cuts this month that include closing seven production sites globally and cutting 11,000 more jobs, taking its total planned workforce reduction to around 20,000.

As part of the cuts, Nissan has offered separation packages to workers at its Canton plant in Mississippi as well as to salaried workers in human resources, planning, information technology and finance, showed one email sent last week.

"While substantial efforts have been made in the U.S. to help right-size Nissan, we need to take additional, limited, strategic action here at a local level," Nissan Americas Chairman Christian Meunier said in the email. "The work we are doing today is crucial for Nissan's comeback - delivering the vehicles, revenue and delighted customers necessary for our long-term success," he said.

Reuters could not determine how many people have been offered buyouts or how many have accepted.

A separate email reviewed by Reuters showed Japan's third-biggest automaker has also suspended merit-based pay increases globally for the current business year.

The automaker said in a statement that Nissan North America is offering a voluntary separation program to a limited group of U.S. salaried employees. It declined to give more details as the process is ongoing.

Cutting U.S. workforce runs counter to President Donald Trump's aim of creating jobs and boosting domestic manufacturing through initiatives including a 25% tariff on imported vehicles.

But Nissan's operating profit margin in North America including the U.S., its biggest market, worsened in the business year ended March, even as it sold more cars than a year earlier.

It offered buyouts to Canton workers after launching a job-cut plan in November and has now followed that up with another round.

Analysts attributed Nissan's troubles to factors including an ageing line-up, a lack of hybrid models in the U.S. and excessive focus on increasing output under former top executive Carlos Ghosn whose near two-decade year tenure ended in 2018.

Separately, Nissan on Tuesday said it had paid 646 million yen ($4.5 million) in compensation to former CEO Makoto Uchida and three other executive officers who left their positions at the end of March.

Nissan has yet to disclose a full list of production sites it plans to close. At home in Japan, Oppama and one other plant are under consideration, sources told Reuters this month.

Nissan has said it will consolidate Mexican and Argentinian pick-up truck production into a single Mexican site, and that Renault will buy its stake in their joint Indian business. It has also said it would close a Thai plant by June.

On Wednesday, Bloomberg News reported that Nissan is considering raising more than 1 trillion yen from debt and asset sales which would include a syndicated loan guaranteed by the UK government.

($1 = 144.0500 yen)