By Foo Yun Chee

AMSTERDAM (Reuters) - The Dutch government is to postpone for a second time opening the mail market because of uncertainties over a level playing field in Germany and industry labour conditions at home, the Economy Ministry said on Friday.

In March, Junior Economy Minister Heemskerk said he hoped to open the market in July, subject to developments in Germany and labour talks between Dutch postal companies and trade unions.

"It is because of the two issues that Frank Heemskerk has always mentioned. The situation is still insecure," a ministry spokesman said.

"That is beneficial for TNT forecasts," said Petercam analyst Thijs Berkelder. He said most analysts will now factor in a partially closed mail market in their estimates for TNT (TNT.AS: Quote, Profile, Research), Europe's second-biggest mail and logistics group.

TNT has the remaining monopoly for letters up to 50 grammes, with the market estimated to be worth about 1 billion euros ($1.55 billion) in 2007.

TNT shares extended gains on the news. They were up 2.9 percent to 26.08 euros by 1522 GMT, outperforming a 0.9 percent firmer DJ Stoxx industrial goods and services index .

ING analysts have said postponing market liberalisation until the 2011 European Union deadline could add 1 euro per share to TNT's valuation.

The Netherlands had previously postponed a full opening of the market, due in January, partly because of the introduction of a minimum wage for postal workers in Germany, which it said impedes competition in a market where TNT had hoped to expand its operations.