Opposition leader Morgan Tsvangirai says the first act of Zimbabwe's new parliament must be to work on a new constitution.

The leader of the Movement for Democratic Change party has been abroad since the bitterly contested 29 March presidential election.

His Friday visit to Northern Ireland for a conference of liberal party leaders is expected to be his last stop before returning to Zimbabwe for a runoff election against President Robert Mugabe.

Tsvangirai claims he won the election. But the electoral commission says he didn't win enough votes for outright victory and has announced 27 June as the date for a runoff.

Sapa