"They have consistently proven themselves at the highest level.
"There is a great feeling of togetherness and belief in the group and this news will only help to strengthen this further."
"I'm really looking forward to having more years coming up with this fantastic club," said Germany international Mertesacker, who has captained the Gunners 16 times this season.
"It took me a while to realise I can be a main part of this squad. Now I want to show that. We need to get everyone ready at this club and get the best out of everyone."
Czech Republic international Rosicky said he signed a new deal because "one big factor is that I want to win the league with Arsenal".
He added: "It's my big goal and I will do everything I can to achieve it."
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