YANGON - Myanmar President U Thein Sein has resigned as chairman of the ruling Union Solidarity and Development Party (UNDP) and his party post was replaced by its vice-chairman U Shwe Mann, according to the party's Union Daily Thursday.

In accordance with the 2008 constitution, "if the president and the vice presidents are members of a political party, they shall not take part in its party activities during their term of office from the day of their election."

As party chairman U Thein Sein was also undertaking the state duty as the president, U Shwe Mann, who is first vice-chairman, helped and undertook the joint responsibility of party chairman.

However, there exists criticism over U Thein Sein's dual posts of government and party, so the handover of the party chairman's post was formerly announced at a three-day party youth function Wednesday.

Chairman U Shwe Mann, who also holds the post of Speaker of the House of Representatives (Lower House), stressed safeguarding of multi-party democratic system  as well as market-oriented economic system.

Quitting his military title of general, U Thein Sein formed the USDP in April 2010 to run the November 2010 multi-party general election, in which USDP won the majority of the parliamentary seats, becoming the ruling party and he was elected as representative to the House of Representatives.

In March 2011, U Thein Sein won the presidential election, swearing in to office on March 30. 2011. The terms of office of the president are five years.

In Oct 17, 2012 the USDP held its first party conference in Nay Pyi Taw but made no major change in its reorganization set-up with its top leadership.

Except addition of two more vice chairmen Thura U Aye Myint and U Htay Oo bringing the number of the vice chairman to three, President U Thein Sein, who was the party's chairman, and parliament speaker U Shwe Mann, who was the party's Vice-Chairman, were both re-elected as in their original posts.

At present, there are 58 legal political parties in Myanmar, of which USDP and the National League for Democracy are leading.