Historic rivals Boston Red Sox and New York Yankees - two of the most iconic franchises in the sport - will face each other at the flagship London 2012 venue on June 29 and 30.

The games will be the first MLB regular season contests played in Europe.

An agreement is also in place for baseball to return to London in 2020, with participating teams to be announced.

The stadium, now occupied by Premier League football club West Ham United, will be able to accommodate 55,000 fans for each match.

Boston will be the "home" team for both games with the rivals never meeting outside of their home cities before.

"Major League Baseball is excited to be bringing one of the most storied rivalries in sports to the passionate fans of London," said commissioner Robert D. Manfred Jr. 

"In our ongoing efforts to grow baseball, there is nothing as impactful as bringing live games and our talented players to fans. 

"This is our most significant endeavor ever in Europe, and we look forward to showcasing Major League Baseball in one of the world's great cities."

Today's announcement was said to be "years in the making" with regular discussions held between Red Sox principal owner John Henry and Yankees managing general partner Hal Steinbrenner.

"There were significant challenges that had to be overcome," said Henry, also the owner of English Premier League side Liverpool.

"We could not be happier that Commissioner Manfred has been able to make this a reality. 

"This series will surely be the most significant international event to date for Major League ball. 

"I can't wait to hear someone shout 'play ball' at London Stadium."

Steinbrenner added: "Bringing these storied teams together for British fans - who have such a profound appreciation for sports at the highest level - only adds to the unique allure of one of the world's greatest sporting rivalries.

"We expect an exciting and intense pair of games and appreciate the significance of representing our sport in such a meaningful way."

Men's baseball and women's softball will return to the Olympic stage at Tokyo 2020, after being axed following Beijing 2008, but their place at Paris 2024 has not yet been confirmed.

Bringing the powerhouse North American league to the continent could be seen as a way of growing the sport in Europe while sending a message to decision makers in the French capital.

Other major American sports leagues, such as the National Football League and the National Basketball Association, have already brought matches to London.

The International Association of Athletics Federations World Championships was held at the Stadium last year.

However, the venue has faced legacy concerns with London Mayor Sadiq Khan taking personal charge of the stadium's future following Newham Council's exit from ownership company E20 late last year.

West Ham are involved in a £100 million ($141 million/€114 million) High Court legal row with the London Legacy Development Corporation over capacity at the stadium, where the club are tenants, and over other aspects such as who pays match-day costs for food, drink, television and hospitality.

Khan had announced plans to take control of the stadium in December after he claimed a "catalogue of errors" by his predecessor as London Mayor Boris Johnson, now the British Foreign Minister.

He said this led to the costs of transforming the venue into a football ground soaring.