(Recasts with tariff timeline, Trump tweet, adds Washington dateline)
* Trump on track with steel, aluminium tariffs
* Trump raises pressure on China trade
* Cohn resignation strengthens U.S. trade hawks
* Fear of global trade war hits stocks, oil, dollar
* EU Commission meets to discuss retaliation strategy
WASHINGTON/LUXEMBOURG, March 7 (Reuters) - U.S. President Donald Trump looked set on Wednesday to authorize steep tariffs on imported steel and aluminium this week as he stepped up pressure against China to develop a plan to reduce its trade imbalance with the United States by a billion dollars.
A day after the resignation of his economic adviser, Gary Cohn, and despite strong push back from Republican lawmakers, the White House said Trump was ready to move forward with his tariffs plan by the end of the week.
Some reports suggested he could sign the presidential proclamation as soon as Thursday.
Trump's plan would impose a duty of 25 percent on steel and 10 percent on aluminum to counter cheap imports, especially from China, that he says undermine U.S. industry and jobs.
The action risks retaliatory tariffs on U.S. exports - not least by Canada and Europe - and complicates already difficult talks on the North American Free Trade Area with Canada and Mexico.
The departure of Cohn, seen as a bulwark against Trump's economic nationalism, clears the way for greater influence by trade hardliners like Peter Navarro, Trump's trade policy adviser, and Commerce Secretary Wilbur Ross.
White House spokeswoman Sarah Sanders said the president was considering several candidates to fill Cohn's position, while Navarro said he was not in the running for the job.
"The presidents got a number of people that could potentially fill that role," Sanders told reporters.
The increased likelihood of tit-for-tat trade measures and its impact on global growth hit shares, oil and the dollar.
Adding to the tensions over the tariffs, Trump doubled down on China, which he accuses of unfair trade practices.
"China has been asked to develop a plan for the year of a One Billion Dollar reduction in their massive Trade Deficit with the United States," Trump tweeted, mistakenly referring to a deficit where Beijing runs a surplus.
He did not give details on how such a request had been conveyed.
In his first tweet on Wednesday, the U.S. President showed no sign of backing down, saying the United States had lost more than 55,000 factories and 6 million manufacturing jobs and let its trade deficit soar since the first Bush administration.
"Bad policies & leadership. Must win again!" he tweeted, a day after saying he did not fear a trade war.
"When we're behind on every single country, trade wars aren't so bad," he told reporters.
CONCERNS OF TRADE WAR
Meanwhile, Europe and the IMF issued strong warnings to Washington to step back from the brink of a trade war.
"In a so-called trade war ... nobody wins, one generally finds losers on both sides," International Monetary Fund head Christine Lagarde said on Wednesday, adding that a trade war would take a "formidable" toll on global economic growth.
In Geneva, China raised its concerns at the World Trade Organization where 17 other WTO members also voiced misgivings.
"Many said they feared tit-for-tat retaliation which could spiral out of control, damaging the global economy and the multilateral trading system," WTO spokesman Keith Rockwell said.
A trade official quoted Canada's WTO ambassador as saying: "We fear that the United States may be opening a Pandora's Box that we would not be able to close."
European Council President Donald Tusk, who will chair a summit on March 22-23 where EU leaders will discuss the threat of a "serious trade dispute", said Trump's view that trade wars were good and easy to win was wrong.
"The truth is quite the opposite. Trade wars are bad and easy to lose," Tusk told reporters.
He was speaking after the EU executive met to discuss a list of 2.8 billion euros ($3.5 billion) worth of U.S. products - from bourbon to Harley Davidson motorbikes - on which Europe could apply a 25-percent tariff if Trump goes ahead.
"We are eager not to escalate this," EU trade commissioner Cecilia Malmstrom said.
"We do not want this to go out of proportion, but ... if it does happen we will have to take measures to protect European jobs."
For those who fear a trade war, the candidates to replace Cohn as Trump's adviser do not bode well: Peter Navarro, the White House National Trade Council head who wrote a book called "Death by China: Confronting the Dragon A Global Call to Action", and conservative commentator Larry Kudlow.
German Economy Minister Brigitte Zypries said: "I hope Trump changes his mind ... It's very important that there are advocates for this in the White House. That's why I'm worried about the latest signals coming from the USA."
Britain, keen to foster global trade relations as it prepares to leave the EU, said it was "very disappointed" by Trump's plan.
(Additional reporting by Philip Blenkinsop in Brussels, Tom Miles in Geneva and Susan Heavey in Washington Writing by Robin Pomeroy and Lesley Wroughton Editing by Hugh Lawson and Nick Zieminski)