By Maiya Keidan and Alexander Hübner

LONDON/MUNICH (Reuters) - Gambling company Lottoland said it was ready to offer up to 76 million euros (£68 million) for German lottery business Tipp24 in a move which could thwart the restructuring plans of Tipp24's owner Zeal Network.

In Germany, official lottery tickets are sold on behalf of the state through authorised distributors locally or online, while so-called 'secondary' lotteries like Tipp24 bet on the state lottery numbers but are actually unregulated.

After German authorities announced plans to tighten oversight of the secondary sector, Zeal decided to pull out of that business, a person familiar with the matter said.

Zeal wants to switch its business model from a secondary lottery to the legal distribution of state lottery tickets. The company wants to keep the well-known Tipp24 brand and through it sell official lottery tickets, the source said.

As part of that plan, it made an offer to buy Lotto24 AG, a former subsidiary that already sells official lottery tickets.

On Friday, Gibraltar-based Lottoland entered the fray with its alternative plan, a conditional offer for Tipp24 pitched at 60-76 million euros, subject to due diligence.

"We believe that Lottoland's proposed offer is superior to the contemplated transaction and... should be put to the shareholders to evaluate," Lottoland said in a letter to the board of Zeal seen by Reuters.

Zeal rejected the offer which it described as "significantly inadequate" and said would deprive Zeal of its most valuable asset.

"The indicative offer from Lottoland is an attempt to buy our core German assets on the cheap," Chief Executive Helmut Becker said in a statement.

Speaking to Reuters, Lottoland Chief Executive Nigel Birrell said the proposed Lotto24 deal would be "value destructive" and there was a "good chance" it would be rejected by shareholders.

Activist manager Burren Capital Advisors on Jan. 4 told the Zeal board its bid for Lotto24 was "not in the best interests of Zeal's minority shareholders".

Top-five Zeal shareholder Marc Peters, who holds 4.8 percent of the shares, on Thursday told Reuters he also did not support the acquisition.

(Additional reporting by Caroline Copley; Editing by Keith Weir and Elaine Hardcastle)

By Maiya Keidan and Alexander Hübner