Brussels- European Union leaders issued a new threat to impose sanctions on Zimbabwe on Friday, one week before the country holds a runoff presidential election marred by widespread violations.

"The European Council (of ministers) reiterates its readiness to take additional measures against those responsible for violence," EU heads of government and state said in a joint statement due to be issued at the end of a two-day meeting in Brussels.

Britain has been heading calls for the EU to get tough on the regime of Robert Mugabe, who is is accused of violating human rights and of ordering the harassment of opposition supporters.

The leaders also "regretted" Zimbabwe's rejection of its offer to provide election monitors and called on the Southern Africa Development Community and the African Union to "deploy a significant number of election monitors as soon as possible and to ensure their continued presence until the electoral process is completed and results officially declared."

The threat came as Zimbabwe's main opposition Movement for Democratic Change candidate Morgan Tsvangirai was said to be considering pulling out of the June 27 runoff because of the escalating violence against his supporters by followers of President Mugabe.

The European Union already has a travel ban on Mugabe and his closest aides.

"The European Council remains deeply concerned by the situation in Zimbabwe and reiterates the need for the upcoming second round of presidential elections on June
27 to be held in a peaceful, free and fair environment in accordance with international norms and standards," EU leaders said. (dpa)