Europe's trade chief accused Nigeria and South Africa on Monday of trying to block negotiations for new trade and investment deals between the European Union and scores of former colonies.

The EU wants to sign new Economic Partnership Agreements with nearly 80 African, Caribbean and Pacific (ACP) countries before December 31, when existing preferential trade rules expire. The World Trade Organisation has deemed those rules illegal.

The 15-nation Economic Community of West African States (ECOWAS), which includes oil-exporting heavyweight Nigeria, has rejected the EU call for new interim commercial deals by year's end, and demanded an extension of the WTO waiver.

"It is quite clear to me that Nigeria, which is the dominant economy in (the western African) region, wants to sit like an elephant in the middle of the road and stop the others proceeding," Peter Mandelson told European Parliament lawmakers.

He also said South Africa was holding back smaller countries in the southern African region from making progress in talks with the EU on issues such as services and investment rules.

Mandelson has said Brussels may have to settle for interim deals covering trade in goods this year before pressing on with more sensitive issues such as services and investment in 2008.

On Monday, he said only a few issues had to be resolved with Caribbean countries and interim, "stepping stone" deals could yet be reached with the Pacific and southern African regions.

Talks with eastern Africa could result in a deal with just some countries in the region but a meeting last week with central African states was "very disappointing" and the EU would try for a deal with the region's banana exporter Cameroon.

Similarly, a "patchwork" agreement might be reached with Ivory Coast and Ghana even if the oil-rich west African heavyweight Nigeria is not included, Mandelson said.

He also said the EU would be careful not to damage nascent industries in ACP countries, something critics such as development campaign group Oxfam have said will happen given the superior firepower of European business.

"Where there is direct competition, in particular in processed agricultural goods and for subsistence products, I have told my negotiating teams not to seek market opening."