The four founding members of the Common Market of the South (Mercosur) -Argentina, Brazil, Paraguay and Uruguay- have started showing concern about Venezuela's capabilities to accommodate to the block, as it joined the group as full member in a record time, sources said Thursday in Montevideo.

Uruguayan officials told weekly economic newspaper Búsqueda that "15 days away from the deadline set for Venezuela to explain how it will adapt to effective mechanisms under Mercosur, the remaining full members are concerned about Caracas' lack of decision."

The sources claimed that before transferring the temporary chair of Mercosur to Paraguay, Brazil reminded Venezuela it was lagging behind as to the presentation of a schedule for enforcement of the common customs tariff and free transit of goods and services, Efe reported.

They stressed that such a schedule "will have to be okayed by the full members of the bloc."

According to Búsqueda, "sources at the Ministry of Foreign Affairs claimed that the full members several months ago forwarded to Venezuela a proposal the country did not answer in subsequent meetings."

The publication added that the major issue is that the deadline for Venezuela to complete adhesion to Mercosur is about to expire.