But it's still not certain when the planes, that were grounded worldwide this month, will be allowed to fly.

Investigators have not yet determined the cause of the accidents.

As part of the upgrade, Boeing will install as a standard a warning system, which was previously an optional safety feature.

Neither of the planes, operated by Lion Air in Indonesia and Ethiopian Airlines, that were involved in the fatal crashes, carried the alert systems, designed to warn pilots when sensors produce contradictory readings.

Boeing said in future airlines would no longer be charged extra for that safety system to be installed.

The Manoeuvring Characteristics Augmentation System (MCAS), designed to keep the plane from stalling, reacts to sensors which detect whether the jet is climbing at too steep an angle.

But an investigation of the Lion Air flight last year suggested the system malfunctioned, and forced the plane's nose down more than 20 times before it crashed into the sea killing all 189 passengers and crew.

The US Federal Aviation Administration says there are similarities between that crash and the Ethiopian accident on 10 March.

Boeing has redesigned the software so that it will disable MCAS if it receives conflicting data from its sensors.

In a briefing to reporters Boeing said that the upgrades were not an admission that the system had caused the crashes.

Timetable
Boeing said a final version of the software would be submitted to the Federal Aviation Authority (FAA) by the end of the week.

But it added that airlines would have to install the new software, give feedback on its performance, and train pilots before the changes could be certified and the planes passed safe to fly again.

A joint investigation by the U.S. National Transportation Safety Board, France's aviation investigative authority BEA and Ethiopia's Transport Ministry is expected to release a preliminary report into the Ethiopian crash this week.

A Boeing official said: "Following the first incident in Indonesia we followed the results of the independent authorities looking at the data, and, as we are always looking to ways to improve, where we find ways to improve, we make those changes to make those improvements."

The sides exchanged views on effectively realizing agreed issues by the Prime Ministers of two countries during the visit of the Prime Minister of the ROK Lee Nak-yeon to Mongolia. Particularly, the parties agreed to collaborate in ensuring preparation works of elevating bilateral cooperation to Strategic Partnership within the 30th anniversary of establishment of diplomatic relations between Mongolia and the ROK, defining objectives in each sector, strengthening dialogue mechanism between the Foreign Affairs Ministries as well as create a channel for multi-sided strategic dialogue and holding the Joint Mongolia-the ROK Intergovernmental Committee Meeting in the near future.

Minister D.Tsogtbaatar introduced his initiative for encouraging young diplomats and asked Korean side’s support on cooperating in arts and culture and information technology, organizing M-K-Pop festival, establishing Korea IT Camp and easing visa condition to families of Mongolian citizens who are working in the ROK under labor agreement.

Moreover, they exchanged views on working together within regional initiatives such as Northeast Asia Super Grid and establishing the East Asia Railway Community and issues of mutual interest on regional and international affairs.

The sides acknowledged to closely cooperate in ensuring stability and building peace on the Korean Peninsula.

The comment comes shortly after talks with French President Emmanuel Macron, European Commission President Jean-Claude Juncker and Chinese President Xi Jinping, who is currently paying a state visit to France.

The Chinese president came to France after his three-day visit to Italy. On Saturday, Rome and Beijing signed the memorandum of understanding on Italy’s joining of China’s Belt and Road Initiative. The move had not been received well by European nations, particularly France and Germany. French President Emmanuel Macron had called for a more consolidated approach toward China among European allies, at the same time as Paris was signing multi-billion-euro contracts with Beijing.

The Belt and Road Initiative is expected to provide effective connectivity and boost China’s cooperation with more than 152 countries in Southeast and Central Asia, the Middle East, Europe, Latin America and Africa via various infrastructure projects, along the lines of the old Silk Road.

The project, proposed by Xi in 2013, promises to significantly boost global trade, cutting trading costs by half for the countries involved. China has heavily invested into the ambitious enterprise with a reported $900 billion having been spent on projects in partner countries. Most of the investment projects of the Belt and Road initiative have reportedly benefitted China’s state-owned corporations.

At the meeting, it was emphasized that the good neighborly relations between Mongolia and Russia has been developing rapidly at strategic partnership level. The sides then exchanged views on bilateral political, trade, economic and humanitarian ties, as well as other cooperation issues including the issue of jointly celebrating the 80th anniversary of the Victory of the Battle of Khalkhin Gol, 70th anniversary of the establishment of Mongolian-Russian joint venture ‘Ulaanbaatar Railway’, and the 60th anniversary of bringing virgin lands under cultivation in Mongolia.

Pointing out the increase in bilateral trade turnover, both sides agreed to discuss opportunities for further expansion of trade and economic relations and cooperation at the Mongolia-Russia Intergovernmental Commission meeting to be held in Ulaanbaatar in the near future.