The United States plans to send two election observers to monitor Myanmar's April 1 parliamentary by-elections, joining observers from Southeast Asian countries to track a vote that will be contested by opposition leader Aung San Suu Kyi, officials said on Wednesday.

The U.S. State Department said Myanmar, formerly known as Burma, had extended the invitation to two monitors following a similar invitation it made this week to members of the Association of South East Asian Nations (ASEAN).

We will obviously take up this offer, State Department spokeswoman Victoria Nuland said, adding that details of exactly who would represent the United States remained to be worked out.

Nuland noted that the limited number of invitations fell short of international standards for election monitoring.

This is a good first step. Burma hasn't allowed international observation before. But it does fall short of international complete transparency on an election.

What we're going to try to do now is work with ASEAN so that we can maximize the impact that we can all have together while continuing to encourage the Burmese to be as open as possible about these election.

Myanmar has asked the ASEAN monitors to arrive in the commercial capital, Yangon, on March 28 -- just four days before the election, which will be held in 48 constituencies.

The move by Myanmar is thought to be an attempt at improving transparency after a 2010 general election that was marred by allegations of fraud, and widely dismissed as a sham to favour a party created by the then military junta. There were no observers or journalists officially invited.

It is unclear whether the United States and other members of the international community, which are reviewing sanctions on Myanmar and has urged fair and fair polls, will consider the small number of prospective monitors sufficient to properly assess voting conditions.

Suu Kyi's National League for Democracy (NLD) has repeatedly complained of irregularities on voter lists, which it says could threaten the fairness of the election.

Myanmar has repeatedly promised to ensure the vote is free and fair and has welcomed Suu Kyi's bid to become a lawmaker, which would be a boost for a legislature that, while grand in scale, has very limited powers.

Suu Kyi's aim, if elected, is to amend a 2008 constitution that enshrines the military's leadership role in politics, which would be a bold move in a country run by the army for 49 years and still led by former generals of the old guard.

(Reporting By Andrew Quinn; Editing by Cynthia Osterman)