AT&T

(T) - Get Report

said Wednesday it will delay an offer to exchange its own shares for shares of

AT&T Wireless

(AWE)

due to a paperwork error. The telecommunications giant also said it will reduce its $10 billion offering of the wireless subsidiary by $3 billion.

The exchange offer, which was to begin next month, is now expected to start in early April. AT&T blamed the delay on the inadvertent omission of some financial data from an electronic file transfer in March to the

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Securities and Exchange Commission

. AT&T said it will be in compliance with SEC reporting regulations by early April.

AT&T also said it plans, subject to a favorable tax ruling, to retain up to $3 billion of AT&T Wireless stock. AT&T offered no explanation, but said it would provide further details "as they become available."

Previously, AT&T said up to $10 billion in AT&T Wireless stock would be

available for exchange, depending on shareholder interest, and that following the exchange, the rest of its interest in the wireless unit would be distributed to shareholders. AT&T has not yet specified a share ratio for the exchange. About 16% of the wireless concern is publicly traded following the initial public offering of AT&T Wireless shares last April.

AT&T has said previously that it expects the wireless unit to become an independent publicly held company by this summer.

The company said the delay of the wireless unit exchange offer won't affect the timing of its plans to split off its broadband and long-distance units.