UNITED NATIONS (Sapa-AFP) - UN chief Ban Ki-moon on Wednesday expressed his "profound alarm" over the situation in Zimbabwe ahead of the upcoming presidential runoff election, his spokeswoman said.

Michele Montas said Ban voiced his "profound alarm" while addressing an informal session of the UN General Assembly.

"The current violence, intimidation and arrest of opposition leaders are not conducive to credible elections," she quoted him as saying.

"Should these conditions continue to prevail, the legitimacy of the election outcomes would be in question," Ban added.

Meanwhile US Secretary of State Condoleezza Rice called Wednesday for the UN Security Council and African leaders to pressure Zimbabwean President Robert Mugabe into holding free and fair elections on June 27.

Thursday Rice was to focus international attention on Zimbabwe when she and her counterpart from Burkina Faso co-chair "roundtable" talks at the United Nations.

US deputy ambassador Alejandro Wolff told reporters here that the roundtable would focus on "obstacles to free and fair elections" in Zimbabwe.

Wolff also said that the 15-member Security Council would hold a formal meeting on Zimbabwe next week and would hear a briefing on the current trip to Harare by UN troubleshooter Haile Menkerios.

He said it would be up to the UN secretariat to decide whether Menkerios himself or someone else would brief.

In a first round of Zimbabwe's elections on March 29, Robert Mugabe's ZANU-PF party lost its majority in parliament -- for the first time since independence in 1980 -- to Morgan Tsvangirai's opposition Movement for Democratic Change (MDC).

Tsvangirai also beat Mugabe in the first round of the presidential election, but election officials said he fell short of an outright majority and must face Mugabe in the June 27 run-off.