Thein Sein, on the first-ever visit to Brussels by a Myanmar president, received on Tuesday new pledges of EU economic assistance coupled with calls to protect his country's ethnic minorities.
The Myanmar leader, setting out on the fourth leg of an historic 10-day tour of Europe, met successively with European Commission chief Jose Manuel Barroso, EU president Herman Van Rompuy, and foreign policy chief Catherine Ashton.
"You have in the European Union a committed and longterm partner for the historic journey that Myanmar and its people have started," Van Rompuy told Thein Sein, who was warnmly welcomed all round for his ground-breaking reforms in the once pariah state.
Since the former premier took over the presidency in March 2011, hundreds of political prisoners have been released and elections held, including the election to parliament of long-detained opposition leader Aung San Suu Kyi.
"The EU and Myanmar are turning a page in their relationship," said Barroso. "More dialogue, more and better aid, more trade and investment."
While EU development aid has more than doubled to around 200 million euros for 2012-2013, Brussels said it was now ready to explore the feasibility of a bilateral investment agreement.
Ashton, flanked by commissioner for industry Antonio Tajani, will visit Myanmar, also known as Burma, later this year to look at further economic support.
The EU has also offered to reinstate a preferential tariffs deal with Yangon.
Thein Sein complained however of continuing economic sanctions against the country, saying "we are one of the poorest countries in the world."
The EU in April rewarded Myanmar's historic changes by suspending for one year a wide range of trade, economic and individual sanctions and said it would "monitor closely the situation on the ground, keep its measures under constant review."
And Brussels on Tuesday made clear it was monitoring minority rights, notably the ongoing conflict in the northern state of Kachin, and communal Buddhist-Muslim unrest in the western state of Rakhine -- where the bloc has provided some 5.5 million euros to help the internally displaced from both communities.
"Important challenges remain. In particular, on the need for a comprehensive peace settlement in ethnic areas," Van Rompuy said.
Speaking through an interpreter, Thein Sein said his government had been able "to reduce a culture of fear" and vowed to continue to work to strengthen democracy. "You have my promise we will continue on this path," he stated.
But groups such as Human Rights Watch urged leaders in Brussels to press the head of state to honour pledges on rights, including a promise to allow th UN Commissioner for Human Rights to set up an office in Myanmar.
There was deadly sectarian violence against ethnic Rohingya Muslims and rights abuses by security forces in ethnic conflict areas, particularly in Kachin state since the resumption of fighting in 2011 against separatists.
The minority, numbering about 800,000, has been described by the United Nations one of the most persecuted minorities on the planet, with thousands seeking refuge in neighbouring countries as boat people.
"Any realistic analysis of the current situation on the ground in Burma would conclude much more needs to be done to entrench reforms," said the group's EU director Lotte Leicht.
Thein Sein, who has already visited Norway, Finland and Austria, will end his 10-day trip in Italy.