(Reuters) - French transport infrastructure company Alstom is in talks over a potential $7 billion (£5.38 billion) acquisition of Canada's Bombardier?s train business, marking the latest attempt by Western rail companies to bulk up in the face of Chinese competition.

Chinese trainmakers CSR Corp Ltd and China CNR merged into CRRC Corporation Limited in 2015 to create the world's biggest rail conglomerate by sales and listed on the Shanghai and Hong Kong stock exchanges.

Bombardier and Alstom have both attempted to merge with German engineering company Siemens.

Alstom has sites in 60 countries, including manufacturing facilities in France, Canada, the United States, Australia, Brazil, Poland, Italy and India and its rail and e-bus division reported over 6 billion euros (£5 billion or $6.50 billion) in orders in the fiscal year to March 2019.

Bombardier has 75 production and engineering sites including in the UK, the United States, Sweden, Spain, Poland, Mexico, Germany, China, Brazil, Canada and Australia and reported nearly $36 billion in orders backlog for its transportation unit in 2019.

The following is a timeline of merger attempts between the three companies over the past three years:

April 2017 - Talks between Bombardier, exploring a possible sale of all or a part of its rail business, and Siemens reached an advanced stage, but stalled because of both compan
ies' desire to keep control of the merged business, according to sources. (https://reut.rs/2u4s6Di)

Sept. 26, 2017 - Siemens and Alstom agree to mergetheir rail operations, cre
ating a European champion to compete with China's state-owned CRRC Corp. (https://reut.rs/2wmZNRj)

July 6, 2018 - Deadline passes for Siemens and Alsto
m to offer concessions to the European Commission, which they did not do. (https://reut.rs/39EmsXG)

July 13, 2018 - EU antitrust regulators open a full-scale investigation into the Alstom-Siemens deal, saying it could reduce competition and lead to higher fares for travellers.

Dec. 12, 2018 - Alstom and Siemens agree to submit measures to the European Commission to reduce their combined sales by more than half a billion euros in a bid to get their planned rail merger approved.

Feb. 6, 2019 - Siemens and Alstom's plan to create a European rail champion collapses after EU regulators block the deal, prompting calls for an overhaul of European competition policy.

Dec. 9, 2019 - Europe's antitrust chief Margrethe Vestager, who blocked the Siemens-Alstom deal in February 2019, says EU regulators would review two-decade old rules to take into account globalisation and digitalisation.

Jan. 22 - Alstom shares hit their highest level in almost 10 years after talk of the possible Bombardier acquisition.

Feb. 12 - Alstom's board meets to decide on a possible offer for Bombardier's rail business.

Feb. 13 - Airbus teams up with the Quebec government to buy Bombardier's 33.5% stake in the A220 passenger jet programme, completing its exit from civil aviation.

Feb. 17 - Alstom confirms it is in talks over a possible $7 billion acquisition of Bombardier Transportation.

Jan. 24 - Bombardier approaches Alstom and Japan's Hitachi as potential merger partners for its rail business.

(Reporting by Sarah Morland in Gdansk; Editing by Tomasz Janowski)